I also start buying around October time adding just one or two things to the weekly shop to spread the cost. I feel happier knowing I have things stashed away so I won't have to dash round the shops for everything in the days before Christmas.
So far I've got:
Two bottles of Cremant for Christmas Eve and Christmas Day.
Scallops in the freezer (we always have shellfish for Christmas Eve dinner)
Beef dripping for the roast potatoes
Stuffing balls in the freezer
Pigs in blankets in the freezer
Cranberry sauce
Turkey gravy granules
Christmas pudding and brandy butter
Crackers
A couple of wedges of cheese but I need more for the cheeseboard
Wine and prosecco
Bottle of Baileys
Foil trays to make washing up easier on Christmas Day
Chutney
Nuts
Crisps
Lebkuchen
Still to get are mince pies, the meat and all the fresh veg for Christmas dinner, Yorkshire puddings, beers, bagels, smoked salmon, cream cheese, chocolates etc. I'll keep adding a couple of items each week as I like just slowly building the stash up!