Outside of Quebec, many universities employ a rolling admissions policy. Unlike a regular admission process with firm application deadlines, applicants are often notified of their acceptance or refusal within a few weeks of applying. The application process typically opens up in the early fall, and it may continue right through the summer. In the case of rolling admissions, your chances of being admitted can be better if you apply early.
In the case of most programs in Quebec universities, however, there are fixed application deadlines (March 1st for fall time studies and November 1st for winter studies), and decisions are typically made after the deadline has passed.