+1(514) 937-9445 or Toll-free (Canada & US) +1 (888) 947-9445
You should call Ircc and ask.
However the law states that as long as you applied for your PGWP before your study permit expired, you were a full time student and you did not work more than 20 hours/week you can start working full time for a period of 120 days or until a decision is made whichever comes first.

i’d still call IRCC and confirm. You should be fine tho.

PS: this is not legal advice. Please seek the services of a lawyer if you need legal advice
 
Hi guys,
I'll soon apply online for a PGWP. Will I immediately receive a letter from IRCC mentionning that I'm allowed to work until a decision has been made ? If not, how can I prove to my employer that I'm legally entitled to work until I receive my PGWP ?