I'd cook them as close to time to go as possible. That way, they'll only need minimal re-heating. Norco's right, though: nothing is lost by reheating, it's just a little bit more hassle when you get there.
Weber Smokey Joe
18" Weber Kettle
22" Weber clone kettle
Curb-foundling char-broil gasser
WSM: Assembled! First cook: 8/25/06
Fanatical devotion to the Q