Without bags and same terminal 2 hours. Different terminals (like ORD) I'd add an hour. With a checked bag - add another hour.

Had 2h10 in YYZ Friday also coming in on TK. That was tight (and no checked bags) since we had to wait 50 mins for a gate at the 500 mid-field terminal and then a bus ride to T1. Made it to US pre-clearance with 10 mins to spare. Not what I'd normally book, but it was the last option of the day and one thing you can count on is that AC is running late - they did not disappoint