I work with WestJet and our priority system is similar to American Airlines. Priority is based on time of check-in. Check-in opens for all non-rev employees 24-hours prior to scheduled departure time. We can check-in online, at a Kiosk, or at the Check-in counter 24-hours prior to the flight. We can start to list for flights two weeks prior to the date of departure, and can list for the return flight (as long as it is booked on the same itinerary) for any date with no time restrictions.