What he said is not correct. You are only bidding with the members of your class.

You will be given a sheet your 1st day in class and a presentation from Crew Planning.

You have xx number of slots for your whole class. Every week of 2015 is available (at least one slot) and SWA does round-robin awards.

Even at 20 out of 20, you will get at least one of the weeks you want.