I'm certainly no expert but I'd cook the day before. Otherwise you're gonna be up real early getting things going and may or may not get the brisket to the "butta" phase.
2004 Weber Performer GREEN
Orange Super-Duper Fast
Taylor Made 9deg. R7TP w/S-Fujikura 6
Rescued 2002 Weber Genesis Silver B Gasser
SJG Tamale Pot Mini Smoker (SJG was a rescue)
18" Gold (rescue) SJS (rescue)
and a Pyro FIL