Your unit will let you know when things begin to fire up, and you should contact them directly for timings.
Normally though, you are 'theirs' from about 1900h Friday and are home Sunday in the late arvo, home in time for supper.
I staffed one of these in 1989, and I don't think timings have changed that much. In those days it was Regina to Dundurn, leaving at 1900h Fridays, arriving at 2200, and departing at 1300h on the Sunday.
Regards,
OWDU