They should just mail it. They may need you to come over, I'm not 100% sure on how this works.
In 3 weeks you can get a SIN card and that's about it.
Stuff like a health card, driver's license etc you should wait until you are actually in Canada.
I would spend those 3 weeks looking at the job market, apartment/house hunting, and deciding if you want to live in Toronto or someplace else. (As a PR you can live and work wherever you want, including Quebec.)