Tim
On arrival, you will clear Canadian customs and it can vary widely, depending on the number of incoming flights at that time. You pick up your luggage in the same space and then finally exit onto the street level. I've spent 10 minutes and 40 minutes in there. 9:30 on a Wed should be quieter

When leaving, you should pre-clear US customs and immigration at the airport and it too can be huge lineups but they are (or used to be quite efficient). Again, assume at least 30-45 min to get thru INS and airport security.

It may also vary depending on which terminal you arrive/leave from as they have been doing work at YYZ. Maybe some others can post more updated info for you.