In my best suggestion, if you are wanting him to stay here with you then he should not travel back home since he needs a visit visa to travel to Canada. Considering he will be married at that time, it is likely they will deny it on the basis that they don't believe he is going to Canada just for temporary reasons. I would say that after you get married submit an extension of his stay but change his conditions to visitor. The reason you could put on the extension request is that he would like to stay after you submit your PR app.
Include a photocopy of your marriage certificate, proof of at least the $550 fees for the PR app paid for, and proof that you can financially take care of him for the duration of his stay. This can be copies of your most recent paystubs as well as bank account printoffs. Proof that you are in a qualifying relationship for sponsorship and that you have already paid the first fees shows dedication to submit your PR application. They will more than likely approve this. Before you mail it, take a copy of everything you included for your own copy in case something gets lost at the visa office and when you mail it, send it through courier with tracking and signature so you have proof that he applied for an extension of his status before it expired. It is recommended that you mail in 30 days BEFORE the visa expires but you could if needed to, submit with 3 weeks left. As long as it is received to them before his status expires, he will he is allowed to stay until he hears back from them. At the moment it is taken 90 days for them to mail back a response to extension request so even if it is refused, you still got to spend 3 extra months together and if it is refused, he will have 30 days from the date the letter of refusal is signed to leave Canada. All in all, most people who do as stated usually get approved for an extension but if he isn't, you will have enough time to work on the application and you could be done through the whole process by the time you get a response back.
If I explained something wrong, I hope a senior member can correct me or suggest something better. And if RobsLuv doesn't mind, I would recommend you talk to her. She is very helpful with everything and has helped me through so much. I hope you find this helpful and good luck.