This is the educated guess, and it’s based off of the fact that November is when the official Avengers: Infinity War trailer dropped.
The trailer likely would arrive online first, but a trailer drop near the end of November seems to make the most sense.
Seeing as how Infinity War also opened in late April/early May (we expect Avenger 4 to move back into April, like its predecessor did), this would mean that the pending sequel is staying on a similar marketing track, getting audiences excited for the conclusion to the battle with Thanos (Josh Brolin) as they head into theaters over Thanksgiving weekend.