Yaar there is no standard timeline for background check. It could take straight 12 months (as in my case) - or it can over within 3-4 months too (yes - quoting these times from Pakistani Spousal Applicants).
It depends on the complexity of your application and also how quickly our pakistani police / state dept cooperated with Canadians. And also how overloaded or busy the Canadian Visa office is which is handling your application. So multiple factors.