CC charged March 2, 2016. Package delivered to the FBI on Nov 10, 2015. Now for the critical part. Did my prints go through? Don't know yet.
To answer some of the questions raised above, please don't wait until the last minute to submit eAPR, give yourself at least 2 days (i.e., submit a couple of days before your deadline). MyCIC can be glitchy at times so better to give yourself some room. As to how long it takes for them to get back with additional docs request (FBI pcc request), the latest trend seems to suggest pretty quickly. Mine came within a week. As far as I know, they have yet to reject as incomplete any app with proper proof that forms have timely been submitted to the FBI.
As to the logistics of uploading docs after eAPR submission, a specific upload field for replacement pcc is added once CIC sends additional doc request. The deadline for that field will be per the extension deadline CIC gives (keep in mind that at first the deadline may appear to ve earlier than what you actually have, but that date will keep shifting automatically every few weeks or so until it gets to the actual deadline). Alternatively, folks have also submitted FBI pcc by raising CSE.
Wishing you all the best.