Since PGWP extensions due to passport expiry have to be filed on paper, it may be faster to use your AOR from your PR application to apply for a bridging work permit online next month (when you're within 4 months of your PGWP expiring). However, if you are okay with simply being on implied status (i.e. you do not plan to travel outside Canada and your employer doesn't mind), then I suppose it doesn't matter if you already have your PGWP extension application in.