Start buying now... Depends if visitors will bring wine, chocs etc.
Make a list of everything you will need
Alcohol
Soft drinks
Table bits - crackers
Nibbles
Decide menu for main lunch (starter, main, puddings) and write down all ingredients involved
Decide on extras Christmas cake.
Then I divide this into two lists.
- Fresh stuff that has to be bought/ordered for Xmas week.
- Stuff that can be bought in advance.
I then carry the second list in my bag and look out for offers on these, but make sure I buy a few things off it each week when doing my normal shop.
Then find somewhere to keep tis stuff sO it doesn't get eaten/drunk before the day.
I also work out a cooking timetable for Xmas day, but to be honest I do as much the day before as poss - lay the table, get all the right dishes etc out. I make my stuffing. On Xmas morning once kids ave opened stockings, dh makes breakfast whils I peel the veg etc and leave in cold water in saucepans on the hob.