Speculation:
@ribbita2012 acct posted Unicode Braille which creates a bridge, some sleuths believe there are 5 parts. First part posted on Sep 15, then Sep 17, then Sep 20 (PT, San Fran time), those are 2 then 3 days apart. Matching this pattern, 4th installment would be on Sep 24, and 5th on Sep 29.