Well I par boil my veggies the day before. Parnips are par boiled and then whilst still hot sprinkled with grated parmesan. I lay them out on a greased (spray oil) baking sheet and fridge overnight, all other veg prepped, however I don't DO fancy veg, I do plain carrots, broccoli, sprouts, parmesan parsnips and sometimes cauliflower cheese (Pre made)
Personally I love roasts as they are bung it in teh oven and do shag all as far as I am concerned. ALL the bits and bobs (bread sauce, cranberry sauce, sausgages and bacon, stuffing) are made in the DAYS before.
Christmas morn bung in turkey, drink champagne, wait until about 1/2 hr before turkey is done, then bung in potatoes, 1/2 hr after that, sausage/bacon, stuffings, parsnips, cauliflower cheese go in as turkey comes out to rest (need the oven space) WRAP turkey in foil and leave while cooking last minute veg (I use microwave or steamer, non soggy veg) and reheating gravy with added cooking juices, bread sauce etc.
Personally don't DO starters, I would do a max of salmon on brown bread canapes or prawns on thai bites (thai bite, blob of TOTAL tzatski, King prawn - mmmm) that can be nibbled as I cook and others mingle.
However I love coking for a crowd and I adore doing roasts.
My main tip is my list.
I work out what time we are going to eat, then work out in adavnce what time things need to go in oven etc. This makes it almost fool proof (do it days before, not on Christmas eve) as you can stick it to the fridge and know exactly when everything needs doing and it it perfectly ready at the same time.