CIC will decide whether to give you extra time or reject your application outright for not submitting PCC. There are cases where they have rejected applicants outright if there was no PCC provided at the time of AOR. And then there are some cases for which they gave extensions. Its totally based on your luck. You have 90 days !! My suggestion is to get all PCCs and submit a complete application.I mean can I submit them later , I still have time for 90 days , however I don't want to hold the process because of PCC। , what do you say ?
Read the cases of rejection here, mostly due to PCCs.
https://myimmitracker.com/en/ca/trackers/cec-e-apr-tracker-express-entry-permanent-residency-application