Call Air Canada and get flight times and reserve a spot for your order and tell them your shipping reptiles.
Pillow case your snakes and package them in a cardboard box lined with 1" styrofoam, you must do this its AC policy. Make sure you have air holes and provide heat / cold packs if needed.
Clearly mark on the box, LIVE REPTILES, DO NOT EXPOSE TO TEMPERATURE EXTREMES in numorous places.
Go to Air Canada Cargo building 2 hours before the flight you booked and they will do the rest for you.