Data Point
Requested Miles 60,000 Marriott transfer on Monday, 1/7/19 to AA Frequent Flyer. Just checked account at 7:30 a.m. EST, and 20K and 5K miles are in account today, Wednesday, 1/9/19. The miles were not in the account yesterday. I do not have any status with the airlines, but am credit card holder in both programs. (not saying that this has any impact at all in timing, just a extra info.)
Good luck to everyone.