The bug was reported on December 8th, 2015 and fixed on February 18th, 2016 which is an unusually long time for Facebook. The bounty reached my account during the middle of March, but Facebook has recently changed their bounty payment processor to Bugcrowd, and now they have weekly payments.
I suspect franjkovic means that there's a queue of lump sums to get deposited to their respective owners, and payments in that queue get processed once per week.
