Add at least an hour onto the turkey cooking time, but don't assume you'll need it. Once the bird is cooked (thermometer if you have one, I don't but a skewer poked into the thick bit inside the thigh, and juices run clear is reliable, and I've never had an under done turkey), take it out of the oven, cover it (in the pan) with poil if it's not already, then with several layers of towels. It will stay hot until you need it. The only thing that is spoilt is that the skin goes soggy. As we shouldn't really eat that anyway as that's where the fat is in poultry, you may not mind but if you want it to eat, as you carve strip off some of the skin and pop it back in the oven for just a few minutes and it will crisp up a treat.
I do this waiting period for half an hour or so anyway as it allows the meat to settle, and the moisture to equalise, and makes carving much easier. But if you are caught out and it's not quite cooked you have a useful back up of time.
Granny was in the catering trade in the 1930s when every penny counted and by doing this to all her meat, could cut it wafer thin so the customers thought they had loads but didn't. This is one of her tips but I've read it in other places too.
For the rest of the meal, prepare as much as you can the day before and practise cooking timings. Make sure you have big enough pans to cook the bigger quantities or everything will boil over or go off the boil. Some veggies like carrots are quite happy to be reheated and potatoes can be par- boiled the day before ready to roast on the day. But green veggies need to be cooked right at the last minute. Gravy you could also make well before the day and just reheat when needed.