Just in case you haven't gone through terminal 3 in YYZ before (it's my weekly route now). You'll first go through immigration agents (can be a line up, even late). Once cleared of agents, you can pick up your bag. I usually have a very short wait for my bag from AA (YMMV). Then you exit the immigration area (where you get pulled for secondary (after getting your bag) if the agent you talked to earlier wants you looked at - which you won't know until this point).
Once cleared here, you can exit to Toronto, or turn to get your connection ** be careful not to walk out (will delay you) **.

Waiting for a bag shouldn't delay you. The only issue I've seen is when one or two flights get in late from 'vacation' places, immigration tends to spend more time talking with those people (as opposed to US direct) and it can get a little backed up. But it's not the norm.

You flight doesn't often leave exactly on time anyway - and if immigration is backed up big time, they'll likely be waiting on lots of people.

http://www.flightstats.com/go/Flight...ightNumber=829