Every US airline will be different. Looking at my old job’s new contract, the company must post the bids by 12z on the 15th of the month. Bidding closes 12z on 18th and the company has to post awards by the end of the 18th. Then a second round of bidding starts on the 22nd for 24 hours. When pilots bid the first set of lines and they have vacation or training days that conflict with the flying the crew planners remove those flights and create new lines that are mashups of the leftovers from the first bid. Some pilots, usually junior seniority, who don’t like their choices in the first bid package can bid to be in the leftover lines. That bid closes on the 23rd and the complete schedule for everyone is published by 17z on the 24.