As they stated, the safety factor in cooling hot food is a major issue.
For our VFW pig roast we cook some in advance and safely freeze in 1/2 pan trays adding apple juice after cooling. We plan to cook as much as possible the day of the event but it is not possible to cook all that day. Our first run is low and slow and then when those go on hold for resting we do a second batch hot and fast. The precooked goes into a 24" "Camp Chef" propane smoke vault that we use as an outdoor oven next to the cookers. We can heat 12 1/2 trays at a time in a controlled temperature. We also fill the warming box on the smoker and have a constant supply always hot and ready for serving.
I hope all goes well for you..
Humphrey's DownEast Beast W/BBQ Guru