I agree with Ward Minter - and if they are coming for lunch - just put it in a little earlier - I always cook mine upside down so the breast will be moist without basting - and I cook it low and slow.
Slice the white and brown meat and put the portions into a deep dish.Ladle some hot turkey stock over the portions. Scrunch up cooking parchment paper and saturate with water. Tuck this in round the meat. Cover dish with tinfoil. This will keep the food moist.Keep warm in a preheated moderate oven. Obviously you don't want to leave it too long before serving.
I assume restaurants must do something similar for the Christmas dinners.