I would cook it until it was done and rested. I would vacuum seal it (separate point and flat if you can not seal the whole thing in one bag) and put it in the fridge until you need it and then put the vacuum sealed brisket in a pot of boiling water to reheat. It will taste as good as if it was served fresh yesterday and still be very juicy. I have done this a number of times and it has always been very moist and tasted great.
BBQ Team: Lawn Guyland Smokers
Stupidity for Dummies
…because sometimes, you just can’t dumb it down enough…