There is very very little you cannot do the day before. I don't buy anything ready made and cook for minimum of 8 every Xmas and spend little time in the kitchen on Xmas day. I do put aside a few hours on Xmas eve (usually in the morning) to prepare though and its makes me feel christmassey to have the radio on with all the christmas songs and a glass of sherry as I go about the prep. now my DC are older I get them helping with the veg as well.
All veg prepped and in pans on hob.
Any stuffing - made in fridge/on trays reasy to just be bunged in the oven. Any roasting tins for spuds/parsnips etc - all prepped ready and in the fridge stacked up for food to be added when ready to be put in the oven.
Pigs in blankets - all made the day before in a dish in the fridge or even on a baking tray (if you have room) so they are ready to just be wacked in the oven/put on the bird when needed.
Cranberry sauce - make 2 days before if you want - it lasts 5 days but I make loads and we like it with the inevitable cold turkey salads that follow the few days after Xmas - so always make mne Xmas eve so it lasts.
Mince pies etc - cook now and feeze and just get them out 24 hours before you want them. Even if you dont make them now - you can make pastry in advance and freeze or refrigerate for upto 5 days.
When it comes to the turkey everyone has their own fave way of cooking and prepping it but I have found a way to cook a bloody big turkey without it drying out and not needing me to go in and baste the thing every 30 minutes. So here is what works for me:
Xmas eve late afternoon/evening I go and prep my bird. Put it on a criss cross of very long foil in a baking tray.
Loosen the skin with my bare hands and shove loads and loads of butter under the skin (dont be stingy).
Then I shove a halves apple, quartered orange or a couple of small satsumas, 1 onion halved and a table spoon of water up its bum/down its neck. Supposed to add flavour - maybe it does but is mainly done for moisture reasons.
Smear more butter all over the birs not forgetting legs.
Then take lots and lots and lots of thick cut streaky bacon and cover the bird taking care to layer the edges of the bacon. Leave nothing of the bird exposed and if this means you need to layer 2 x with bacon - thats fine. This helps prevent the bird drying out and the flavour sinks into some of the meat. Be extra generous with the bacon in places like the legs which will cook quicker.
You can add some pigs in blankets too. Last year I put these all over the bird at the start of cooking (and removed them after an hour - kept them warm until serving in the plate drawer/grill/top oven).
Then wrap the bird with the foil taking care to leave a space between the foil and the bird - creating a little oven.
Bung it in fridge or if room is too tight and its cold enough we have used our garage (that is free from wildlife/hungry pets). Just before going to bed I leave it out Over night somewhere appropiate to raise it to room temperature (ish) as apparently you should before cooking (according to my nanna) - usually a unheated utility room/porch/kitchen windowsill.
On Xmas morning as soon as the kids wake (somewhere between 6 and 7.30am) we stall stockings for 5 minutes and the first thing we do is switch the oven on (same time we pop kettle on for our morning cuppa) and whack it in the oven.
I wack mine in as 180 (fan oven) for 45 minutes (set a timer to turn it down) then turn right down to 150 for X hours.
I then spend very little time switching the veg on roasting veg etc as everything has been prepped the night before - I even lay the table Xmas eve with the kids helping.
I honestly spend hardly anytime at all in the kitchen on Xmas day - and we usually eat somewhere between 1 and 3pm depending on the size of the bird and how early/late we wake Xmas day.
Hope something from this helps you a little. Remember that whatever you do - try and enjoy it and dont get stressed. Radio, pinny and xmas tipple are essential tools!!