Your PR application is based on the employment information which was set in your PNP application. This is also why you have a closed work permit right now. Basically your employment, which AINP deemed worthy enough of nomination, is your "permission" to apply for PR. Without that permission you're not allowed to apply for PR.
If you change jobs, the basis of your permission is invalidated. You're obligated to tell AINP that your employment has changed, and they will investigate your new job and determine whether or not that still qualifies you for a nomination. If you keep on doing the exact same work but just with a different employer, it might be OK with AINP. But it's not safe to assume so (and do NOT even think about not telling AINP - if and when you're caught, you can be denied entry to Canada for misrepresentation). If AINP decides that your new job does not qualify, they will withdraw your nomination and inform CIC that your PR application has become invalid. Then, because your PR application has been invalidated, technically your temporary work permit is invalidated as well, because you received it on the basis of being approved for AINP and PR processing.
So yeah, it's a bit of a harsh game.
When you have less than 4 months left of your current work permit, you can apply for BOWP (Bridging open work permit). You are allowed to use it with another employer, BUT you still need to maintain your AINP employment terms. So if your nomination is based on full-time employment at certain tasks in your current company, you must keep on doing that (and have proof of doing so too, through paystubs, company records etc.).
So basically what BOWP with an employment-driven PNP does is, it allows you to get a second job in addition to your original job, if that's what you want to do (to get more money, or more experience, or whatever). But again, you have to be able to prove that you're still complying with the original AINP terms. And obviously you still have to stay in Alberta for both jobs.
My advice is, if possible, don't change jobs until you get PR. If you're under threat to be fired, you can try to talk to your HR manager and ask for their understanding to keep you until your PR comes. Be super crazy nice and productive to show them you're worthy. If you hate your job, just suck it up and pretend to love it for a little while longer. Otherwise your entire process may have been for nothing. Once your PR goes through you can do whatever you want, and it'll be worth it.
Also, don't follow other people's timelines too closely. CIC is under lots of changes right now (mainly because of Express Entry) and they're not operating in the same pace and schedule that they were last year or earlier this year. And there's an enormous amount of fluctuation between individual applications as well.
That said, if you've been in process since September (I assume you applied sometime early this year), like joshy said you shouldn't be too far off. Just don't make any plans where you're suddenly left without valid status or disqualified from AINP.
