If you are travelling to a Canadian or international destination (except the United States), you must go through security screening at checkpoint A.
Screening checkpoint A opens at 03:00 a.m., every day.
If you are travelling to the United States, you must go through security screening and U.S. customs at the U.S. CBP checkpoint in checkpoint C.
Screening checkpoint C is open from 04:15 a.m., every day.
Please note that these times are for reference only and are subject to change.