We recommend arriving at the airport 3 hours prior to your departure time for international travel and 2 hours prior for all domestic flights.
Now that the snow birds have flown home I would say an hour and a half. They don't have an international terminal so there is no difference between international and domestic. You will do your customs in Toronto no matter if you fly WestJet or Air Canada. If you have a Nexus card you will fly though security. 3 hours is not necessary.
Three hours minimum
The airports official statement will be three hours for international flights. Chances are two hours might do though if during non peak hours
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