Depends on the loads, and the airline. American leads the industry in last minute ticket sales. I've sent people on buddy passes when a flight is wide open at 10pm the day before, only to find out the plane is oversold by morning.
So as others have pointed out, be flexible.
Also, do exactly what the owner of the passes and all uniformed employees tell you to do. At my company, I can lose my travel benefits for something someone I gave a pass to did.