Peel potatoes and soak in water.
Peel and cut carrots into batons, soak in water.
Clean sprouts and cut their crosses, wash in salty water.
Peel and chop parsnips and butternut squash, airtight tub with no water. Onions and garlic ditto in separate tubs.
I usually only remember to make my herb butter that day, but try to so it's soft and ready next morning.
Make the stuffing, including cooking the sausage meat.
Last year, I did brine the turkey which I thought was nice but DH was sceptical.
Make Santa's cookies (from scratch some years, just slice and bake frozen dough others - I freeze half a batch earlier in December).
That's probably about it. It doesn't take too long because we do it together as part of the annual slowdown. On Christmas morning, we are out for mass and a couple of family visits before coming back to get turkey into the oven, so not needing to prep at that stage is good - cook some M&S nibbles while we get butter and stuffing into the bird and fire lit, throw bird into oven, open wine, start opening presents with nibbles to sustain us. Turn on spuds or whatever the next task is when someone goes to refill wine glasses.
The nibbles are our starter, we don't do big desserts (proper pudding is steamed to eat much later after cheeseboard), so it is a roast main course to cook really.