Hi! My wife and I are in the same frustrating situation: PRV app sent last December. CSQ received. TRV refused! Etc.
Possibilities for the 8 months (80% of cases) starting point:
1) date when PRV application is received in Mississauga
2) date when sponsorship approved
3) date when CSQ is given (for Quebec only)
4) date when application is received in Moscow (according to e-CAS and CAIPS/GCMS)
5) date of AOR letter
6) date when Moscow status turns to "in process" and all CAIPS/GCMS steps (ex. Security) turn to "Started"
My guess (it's only a guess): "8 months" starts with #6 but you will only know one month later at best since e-CAS is unreliable and GCMS (formely CAIPS) notes are sent to you ALWAYS 30 days AFTER being generated for internal review (confirmed by ATIP officer). Other possibility is #5 but I'm afraid it is just wishful thinking on our part

Hang in there!