"(With) a grain of salt", (or "a pinch of salt") is an idiom of the English language, which means to view something with skepticism, or to not take it literally. 
BoC began 2016 by breaking their silence after "Tomorrow's Harvest" by releasing two new remixes one month apart from each other, Mr Mistake by NEVERMEN and Sisters by Odd Nosdam. The latter was accompanied by a video  which was formally released on February 22nd. This led to some speculation that some new material could be in the works.
After a few months passed, they recaptured the attention of their fanbase with an innocuous post to their generally dormant social media accounts on June 6th, 2016, linking to an existing fan made video for "Macquarie Ridge". A month later, on July 7th they retweeted another fan video of the "Broken Drum by Beck" remix that had been posted to Twitter on July 2nd.
They tweeted once again, this time a Youtube link to "Peacock Tail" on July 31st. The last post raised some uncertainty as to whether they would continue posting in a 6/6, 7/7, 8/8 type frequency.
Around this same time, ASCAP entries for a release entitled "Harvest Ritual" and Untitled (Machinedrum reconstruction) were discovered , but quickly disappeared after they were noticed and the former subsequently waved off  as an old Tomorrow's Harvest related entry by someone  making their first (and still only) post on the Twoism (messageboard). After 8/8 came and went, the next known date of interest was 8/22 (the 20th anniversary of the system date on the Cosecha-transmisiones console) but this date also passed without incident.
With 8/8 and 22/8 eliminated as possibilities, what's the next date that would make sense for them to make another appearance out from the ether?
They finally posted a fan video for "Nothing Is Real" on August 24th which didn't seem to follow any type of previously speculated upon date related logic.
They posted again on October 14th, this time for the song "Left Side Drive".
Over the span of the few months described above, they had begun liking various fan posts on Twitter, seemingly at random, many of the fan posts including pleas for new material or involving the liking of tweets that included their own music. This activity slowed down as time went on, briefly peaking at 49 likes before dropping back down to 48 likes, before going up to 49 likes again in February 2017 - the original 49th liked post was deleted by its author, so keeping the tally set to 49 likes seemed important to them at this stage.
They posted a new fan video for "Open the Light" on December 8th, alongside a simultaneous heavy revamp of their Youtube channel playlists, which had been in need of some upkeep as by that time, as there were multiple broken or delisted videos from over the years. What was interesting about the "Open the Light" post is that it wasn't cross-posted to Facebook, the same as "Peacock Tail" back on July 31st. I feel that these omissions from their Facebook account weren't an accident but rather, those 2 entries were only relevant to a pattern that they were establishing at their Twitter account, but more on that in the Posting Details section.
Rather than a new release announcement at the end of the year, the Youtube video channel revamp seems to have joined the campaign midway to serve as a map of sorts, providing vague hints to assist in navigating the numeric trails being blazed at both their Facebook and Twitter accounts for those who were trying to pay attention. I'll go into more detail on that as the timeline continues to progress.
After the playlist revamp and the "Open the Light" posting on December 8th, they went silent for the rest of 2016.
BoC returned to Twitter on March 28th, 2017 with a posting of the "Dayvan Cowboy" video. Shortly before this (sometime within the several hours prior to the Dayvan Cowboy post) they deleted an old tweet from March 11th, 2012.
On June 7th, 2017 they announced that a new run of their green t-shirts had been released for sale. They liked a fan's post about the topic from the same day.
They announced the release of a picture disc for their Nevermen remix for Mr. Mistake on June 17th. They retweeted the same information about the release from an online publication on the same day as their own post. The picture disc will be released July 21st.
Now that the events have been summarized, it's time to get to the details. As described above, each social media network account seems to have its own unique pattern, but the same crucial end points. Twitter is the most plentiful (and therefore easiest to pick out a method to the madness) so it's best start to start there with a list of the dates and posts so far:
6/6 - Macquarie Ridge
31/7 - Peacock Tail (2005) - 2:25 PM ATZ
24/8 - Nothing is Real (2013) - 2:57 PM UTC +2
14/10 - Left Side Drive (2006) - 3:11 AM UTC -6
8/12 - Open the Light (1998) - 10:57 AM UTC +2
28/3 - Dayvan Cowboy (2005)
7/6 - Green T-Shirt announcement*
17/6 - Mr. Mistake Picture Disc Announcement (released 21/7)
12/9 - Amo Bishop Roden (2000) - 11:32 AM UTC +3
12/9 - Mike Sandison tweeted - 12:28 PM UTC +3
27/9 - An Eagle in Your Mind (1998) - 3:11 PM - UTC +7
- There was a Like related to t-shirt announcement on same date (June 7th)
- A retweet of the picture disc announcement accompanied their own tweet (June 17th)
- The main pattern to follow for 2016 involved multiplying the date and month together for the posts when both numbers are divisible by 4. We add up to 24 in other even numbered months. We subtract down to 24 in odd numbered months, the odd months are also preceded by a retweet.
- For 2017, we ratcheted down by halves starting with 84, followed by 42, followed by 21. An Eagle in Your Mind represents 2017's version of Macquarie Ridge; the bookend value is 36 in both cases, we multiplied to get there in 2016, we added in 2017.
- There is an overall pattern starting on June 6th 2016 through December 8th, 2017 with values incrementing by 55 or 110. They only broke this pattern early on with Nothing is Real on August 24th. Nothing is Real should be thought of as a disrupter; it's only useful purpose is the fact that it has the same timestamp as the Cosecha console:
The pattern is as follows:
6/6/16 -> 31/7/16 (55 days)
31/7/16 -> 24/8/16 (24 days) 24/8/16 -> 14/10/16 (51 days)
14/10/16 -> 8/12/16 (55 days) 12/8/16 -> 28/3/16 (110 days) 28/3/17 -> 3/11/17 (220 days) (noting the 15 day gap between 12/9 and 27/9, the reverse of 51 days in 2016)
3/11/17 -> 28/12/17 (55 days)
- The still photo for the Peacock Tail video (NBC Peacock logo) was first debuted on May 22nd, 1956 (22/5) - the tweet was posted at 2:25 AZT (or, New Brunswick, Canada time) - add 522 and 225 together to get 747. More importantly, multiply 22x5 to reach 110. 110 is a key number in the flow of the pattern between both years shown above.
- Based on the rules above, omitting any retweets, the main numeric pattern for 2016 should be read like this:
6/6 - 36
31/7 - 24
24/8 - 192
14/10 - 24
8/12 - 96
2017 was a mirror of 2016, taking advantage of the fact that the 2016 numbers are divisible by 6, the 2017 numbers are all divisible by 7.
28/3 - 84
7/6 - 42
21/7 - 147 (84 + 42 +21 = 147 - Mr. Mistake picture disc)
9/12 - 21
9/27 - 36
Additionally, the top 2 songs listed on their Soundcloud account (Palace Posy and Split Your Infinities) are playlist entries 14 and 126 at Youtube:
14 - Palace Posy
126 - Split Your Infinities
Let's take special note of the timestamps on certain tweets and talk about the mirroring aspects of the 2016 sequence vs 2017. Many of 2016s posts are "negative" and have a "positive" companion on the 2017 side.
In 2016, the sequence begins with "6/6/6", the 3:11am timestamp is hidden in Left Side Drive and can be seen at UTC -6 - the distance of time between Nothing is Real and Left Side Drive is 51 days, the same length of time as the siege in Waco, the overall 55/110 sequence is broken for the first and only time at that point.
In 2017, the 51 day length of time is reversed to 15 days using Amo Bishop Roden, 3:11pm now hides in UTC +7, the larger sequence stands unbroken in 2017 when viewed from start (28/3) to finish (28/12) (220 + 55 days)
31/7/16 - 2:25 PM (New Brunswick Canada time) - The peacock logo was first used by NBC on May 22nd, 1956. We can use that date as a clue to the time zone for this post. Aside from 522 + 225 = 747, we use 5x22 (110) as the number of days between the last post of 2016 and the first of 2017, and double it (220) for the length of time between March 28th, 2017 and November 3rd, 2017.
24/8/16 - 2:57 PM UTC +2 - The idea of this post is to tune your time zone to +2 UTC so that the post's timestamp matches the Cosecha console. This post is the "fnord" of the sequence. It breaks 2016's overall sequence, when added, it becomes 32 (the opposite of 23 for you Illuminatus! buffs), the negative connotation of "51 days" which is later reversed in 2017 down to the number 15 - however, that UTC +2 timezone becomes useful on 8/12/16.
14/10/16 - 3:11 AM UTC -6 - on March 28th, 2017 (the first day of the 2017 sequence) an old tweet from 11/3/12 was deleted from their timeline which brought this post into focus. Conceptually, the still photo of this post is in Banff National Park, which is UTC -6. In 2017, the presumed final post has a timestamp of 3:11 PM when we use UTC +7 instead.
8/12/16 - 10:57 AM UTC +2 - The final post of 2016. When tuned to UTC +2 per Nothing is Real, the time is 10:57 AM. Other than the :57 part, it's essentially a reverse of the 2:57 PM timestamp if you look at it as a 12 hour window and am vs pm. 10 x 57 is 570. If we add 570 days to 6/6/16, we land at 28/12/17, the presumed end of the sequence.
12/9/17 - 11:32 AM/12:28 PM UTC +3 - This is a tricky one. BoC tweeted Amo Bishop Roden and 56 minutes later, "Mike Sandison" tweeted again linking back to the official account. Treat these as a pair that add up to a perfect 24 hours. 28/12/17 is also the presumed end of the sequence. Remember that "Palace Posy" is the top song on their Soundcloud. We track it down to video 14 on their Youtube playlist, and it's what appears to be a very Russian video. The fact that its to date the only video published by this account makes it seem like another one of those burner accounts in the spirit of Atalanta Fugiens. Anyways, Russia is +3 UTC - when we apply UTC +3 to the tweets, we get the above timestamps.
27/9/17 - 3:11 PM UTC +7 - Conceptual mirror of the 14/10/16 post. Same timestamp, but pm instead of AM, using +7 UTC instead of -6 UTC.
Going back to 2016, the Broken Drum retweet set up its own sub-pattern starting in July 2016. The original posting date (7/7) is obfuscated on Twitter because it's a retweet, but it was mentioned on the Twoism (messageboard)  on the day that it was first posted. This means that there were posts on 7/7, 31/7, and 24/8 - the commonality is that the posts were separated by 24 days each. The retweet approach seems as if it was intentional, to separate it from the main pattern and hide the existence of the smaller pattern.
Reflecting back, this odd post was likely a subtle hint that the number 7 or even 14 (7+7 given the retweet date, or 7x2 given the original date) would be important down the road, just not right then.
Ultimately, I feel that this retweet represented the upcoming broken pattern by Nothing is Real - 24 days preceding it, 51 days following it. It also served to obfuscate the 55 day period between Macquarie Ridge and Peacock Tail, and to get people thinking about 6/6 -> 7/7 - 8/8 early on, rather than a more complex sequence that would stretch out for over a year instead of just a few months.
Facebook has its own unique pattern, which only utilizes certain crossposts from Twitter. This makes the fact that something is afoot a little more palatable to the average person than the more complex Twitter pattern. The main purpose of this is to clue us into 32+23 = 55, the same way the Peacock Tail tweet gave us 110 buried in its timestamp. As I mentioned in the Twitter section, for Illuminatus! fans, 32 is the fnord, 23 is what we really want.
Left Side Drive stands in the middle to represent the mirror, as it works in 2016 as 24 and 140 in 2017.
Note that of the 2 posts in 2017, the date increments by 10 each time - 17 -> 27. There is no 37th of the month, but if we add 37 days to 27/9, we land on 3/11/17.
6/6/16 (6x6) = 36
24/8/16 (24+8) = 32
14/10/16 (10+14 or 10x14) = 24 or 140
17/6/17 (17+6) = 23
27/9/17 (27+9) = 36
Their approach to their YouTube playlist structure has been thoughtful and at times playful. Try subtracting the numbers of some of the entries from the overall number (145) to se what type of "companion" you end up with (for example, 72 and 73 are "SATellite ANthem ICarus" and "XYZ", interesting after they spelled out L-M-N-O-P with their first few social media posts) You can also add some of the duplicate song values together to see where you end up. They might ask you to do something like "Split Your Infinities" when you find a third instance in the list of the first 2 songs that you added together, for example.
Example of a playlist easter egg:
In the end, it's impressive to witness the care that went into assembling these playlists as a companion to what they have been establishing at their Twitter and Facebook accounts. It provides information that leads one to speculate on future posts. The only drawback to the playlist assembly is that due to the number of repeats, and the proximity of some of those repeats to each other, it detracts a bit from being able to appreciate the playlists at face value. The playlist construction definitely prioritizes the subliminal/easter egg aspects over providing a good flow for the everyday casual listener.
It's worth noting that given the speculation relating to date reversals elsewhere on this page, the main video playlist was heavily revised on December 8th, 2016 to coincide with the Open the Light tweet. A look at the account's "About" page says that it was originally created on August 12th, 2006. (12/8/06 -> 8/12/16)
Playlist entries 24 ("New Seeds")  and 42 ( "csch"  are interesting as the first represents "Seeds" and the latter represents "Harvest" - this lines up with the fact that noteworthy entries incremented by 24 last year, and 21/42/84 in 2017. Again, a representation of the mirror between years.
Nothing is Real is video 15 - if you recall, it broke the pattern with a 51 day timespan in 2016. Another reversal when we consider the Open the Light tweet to be the end of 2016 and the beginning of 2017s sequence.
Video 146 "Echus" was added to the video playlist on April 3rd, 2017 (3+4=7). Echus appears elsewhere in the playlist at position 140 with a different video. The new video ends in a plane crash and has a description of "8/10/84" - presumably when the crash took place. It should be noted that "146" could be read as 14x6=84 (posted one week after the Dayvan Cowboy tweet, which was March 28th (28x3=84)
Most importantly, when we stack the posting and event dates, we come up with some other interesting stuff, drawing parallels between Tomorrow's Harvest's release date and the presumed new release date. Take note that the years are each 16 away from 100, which means they both add to 100:
TH: June 10, 2013
(8-2) = 6
(2+8) = 10
6 + 10 = 16
New release: December 28th, 2017
(2+10) = 12
(8+20) = 28
28 - 12 = 16
Playlist entries 85 and 43 are worth noting, as they are both "Beware the Friendly Stranger" - subtract them from each other to reach 42. Aphex Twin had a countdown running that was meant to end on July 6th (6x7=42) before it was altered to finish at a later date toward the end of the countdown (apparently now ending July 20th, as of this writing)
A particular section of the YouTube video playlist is slightly suspicious. If we add together the current number of tweets and likes at their Twitter account and correlate that to a numbered playlist entry, we see a possible roadmap to future posts. Over the past few months (since the playlist re-order) that number was holding steady at 79 - "Over the Horizon Radar" until June 7th 2017.
Over-the-horizon radar, or OTH (sometimes called beyond the horizon, or BTH), is a type of radar system with the ability to detect targets at very long ranges, typically hundreds to thousands of kilometres, beyond the radar horizon, which is the distance limit for ordinary radar.
The sum briefly dropped to 78 "Hey Saturday Sun" on March 28th, 2017 when they opted to delete a tweet from March 11th, 2012. The deletion of this tweet is interesting for a couple of reasons - first of all, it is the only post that has been deleted thus far. If we think of 2017 as somewhat of a reverse of last years sequence (even though its actually 6s vs 7s), perhaps this means November 3rd (opposite of March 11th) is a relevant date down the road.
The drop to 78 ("Hey Saturday Sun") is worth noting for another reason as well. You can isolate either 3 letter word and the remaining characters in the song title add up to 11:
Hey/Saturday Sun (3/11)
Hey Saturday/Sun (11/3)
The deleted tweet was soon replaced with a tweet of the official "Dayvan Cowboy" video, bringing the sum back to 79.
The Mr. Mistake picture disc was announced on June 17th. If we look at the playlist entries of each tweet in 2016, ignoring Peacock Tail (not in the playlist) and Nothing is Real from 24/8, we have the following:
Video 6 - Left Side Drive (14/10/16)
Video 1 - Open the Light (8/12/16)
Video 7 - Dayvan Cowboy (28/3/17)
These are the entries from 2017, and correlating the sum of tweets and likes at the time that they were posted in relation to the video playlist. Note that the overall count incremented by 2 on two separate occasions - June 7th and June 17th. In the case of June 7th, they liked a fan's post that was in response to their initial June 7th posting, and June 17th, one tweet was a retweet, one was their own tweet about the same topic (the Mr. Mistake picture disc). I feel that this is what they were hinting at with the repeating Twoism videos - 80 and 81 are a pair, and 82 and 83 are a pair.
March 28th (28x3) = 84 - entry 79 "Over The Horizon Radar"
June 7th (7x6) = 42 - entry 80 "Korona"
June 7th (7x6) = 42 - entry 81 - Twoism Sunset
June 17th - entry 82 "Twoism"
June 17th - entry 83 "Tears from the Compound Eye"
July 5th - entry 84 "Ready Lets Go"
September 12th - entry 85 "Beware the Friendly Stranger"
September 27th - entry 88 "Pete Standing Alone"
September 28th - entries 90-99 (likes on twitter)
November 3rd? - entry 100 - "Boards of Canada"
Most importantly, Mike Sandison's tweet arrived less than an hour after hitting 85 combined tweets and likes. This was followed by a couple more likes, and "An Eagle in Your Mind" was 88 on 27/9/17. One more like followed that day, followed by 10 more likes (all relating to a desire for a new album) on 28/9/17.
This leaves us at:
36 Tweets 63 Likes
This sum was reached exactly 36 days before November 3rd 2017. Let's think of March 28th 2017 as the beginning, September 28th as the end of the innocuous activity, and December 28th as the very end, the payoff.
28/3/17 -> 28/9/17 -> 28/12/17
Doing something similar in 2016 with the pair of Left Side Drive posts gave us Tomorrow's Harvest's release date (June 10th):
14/6/16 -> 14/10/16
In April 2017, they updated their official SoundCloud page with most of their official content, as separate lists of tracks and a list of albums. The number of total songs is 69, but should be 70, because there is a "broken" track. On April 17th (4+17=21) followers received a notification that a Geogaddi playlist had been created. Later that day, the playlist was deleted. No other albums have a "playlist" per se, so this was unique. Examining the tracklist of Geogaddi further, it showed that track 21 (You Could Feel the Sky) was not present, but had Aphex Twin's Jynweythek Ylow in it's place. Additionally, Geogaddi was published to Soundcloud as being released in 2007 rather than 2002.
We pair these two mistakes together (2007 rather than 2002, track 21 replaced with an Aphex Twin track) and we end up with the release date of the Mr. Mistake vinyl (7/21)
The Aphex Twin track he remained in place of You Could Feel the Sky since April. Since then, Tomorrow's Harvest was added as an album. In the case of this album, take note of the sequence of the first few tracks under the "All" view - 10-11-2-17-14
Putting 10 and 11 out front is slightly suspicious since we seem to be working in iterations of 7 this year and counting down from 84, and they happen to add up to 21. However, when we cross reference these entries to the Youtube video playlist instead (the same as we did to hash out the date of the Mr. Mistake announcement using tweets) these two songs are entries are 14 and 126 which add up to 140, a recurring number buried in the sequence.
This means that we may be counting down like this: 84 -> 42 -> 14 instead of assuming 21 as the final entry. This makes November 3rd an interesting date, especially considering the March 11th tweet (opposite date) which was wiped out on the first day of proceedings of the 2017 pattern.