O.k. thanks. So I can only change it today? I don't have the extra 90 days? And what do I do about my application?
Yes, only today. The 90 days starts when legal status stops. As you applied for a work permit, you will have legal status until a decision is made on that app. If the decision is a normal refusal, you will be out of status as of the day of the refusal. If the decision is a rejection as incomplete, you will be retroactively out of status as of tomorrow.
You can withdraw the PGWP app once you get your visitor extension submitted.