You can able to work full time as per the implied status of PGWP but some people recommmanded to takes an extension with the explanation letter if in case you will get a refusal on the PGWP, as per rules you need a valid status to reapply or for reconsidration.as per before, the processing time was no over the 3 months and a CIC already give 3 months extra on study permit to cover the PGWP processing times.
but now due to the corona study permit processing times already high so it's not worth it. if your study permit already expires so you also brake a rule to be renew it before expire. i also in the same situation and hope to be approved. I had some parttime study.