I am just curious. I expect PPR anytime now. When can I change jobs? After getting my passport back from visa office or after I have done the flag pole?
You haven't provided enough information for anyone to answer your question. We would need to know how you have applied for PR, what kind of work permit you hold now, etc.
You can only change jobs once you are actually a permanent resident. Getting your passport back from the visa office doesn't make you a permanent resident. You have to officially land.