When his work visa is about to expire, you can apply to change his status to visitor based on your intention to file for sponsorship. If you are already married and have already filed for sponsorship at that point, even better. If you file inland, you can send the visit status request with your application as they both go to Vegreville. If you file inland, they will not deny his request for visitor status as it is a requirement for the inland application that he stays in Canada. If you file outland, it is not a requirement for him to be in Canada so they could deny his visit status request but I have yet not heard of somebody who already was in Canada who was not approved to stay as a visitor while filing for sponsorship.