CongratulationsMy final timeline appears like so:
AoR: December 21, 2017
PPR: May 11, 2018
Submission of passport to local VO: May 15, 2018
Approval (on account) and PP dispatch (CoPR): May 22, 2018
Will collect the CoPR tomorrow and book my first landing ASAP.
Luckily, my entire "journey" was smooth. No ADR, no phone calls. Very fortunately, my entire application, along with the FBI PCC, was complete and RPRF paid at AoR. I just had to wait the 4.5 months out. Sincere thanks to this community for all the sharing they do.
I'll post my landing experience in a few months, and continue to monitor/help out folks on this thread for the near future as best I can.
Good luck for the rest who are still waiting. It'll come soon -- just be patient.

May I know if your case was fsw;-o and what was your visa office ?
Regard
Gary