Well, I think, if you all apply together, then your application will be processed within the time period specified for issuing Visas to "Students", (doesn't matter even if your Husband applies for a "Work Permit") because you (the student) is the "Principal Applicant". So you will all get your Visas together (if approved). I am not 100% sure about it, Experts plz help. Or best, apply for 2012 fall session. That way you will have sufficient time.
Getting "Open Work Permit" or even a TRV for student's spouse from South Asian countries is tough. It depends on your Husband's qualification & current job.
Make sure "Visa Officer" MUST NOT think that the main motive of your going to Canada is for your husband to find a job in Canada, and your study visa is just a cover-up.
The best way to prove this is by showing that your husband has a stable, established, well paying Job/Business in Pakistan.