as i heard, while filling up the forms for labor market opinion from labor board, there is a section where they ask if the company wants to sponsor for PR-ship. so, if the company fills that part and gets the approval then you should be fine. since the company would have immediate need of labor, in most cases, you would probably be given work permit to start serving the company while the PR gets processed.
again- this is what i heard.

request for sponsor after u start working.