I personally would still vac seal for overnight. Let the meat rest a bit after its done, vacuum seal it up, then put it in the fridge (in an ice bath would be best). A couple hours before serving time id pop the vac seal bag into almost boiling water to let the meat come to temp (id use a souse vide, but not sure if you have one). Otherwise if no access to boiling water, id take it out of the vac bag and wrap it tight in a crockpot bag and heat that in the crockpot for a couple hours on high with some water in the base of the crock pot.
Anyway, this all seems a bit involved, but IF IT WAS ME, and I was cooking to impress I would do the most I could to make it taste fresh off the pit for that engagement. IMHO, its no question, the vac sealer will make a difference even over night. If you don't have a vac sealer put them into some good gallon or so bags and get all the air out using water displacement (dip the bag into a sink filled with water to let the air out the top).
What did you end up doing and how did it turn out?