Shopping for Christmas food can be a nightmare. The shops are packed with people and finding what you want can be difficult. Do you think it's best to shop early or wait close to the day? You need to wait for Fresh Produce like cream etc and then you run the risk of missing out on what you need.
I did mine about a week or two ago for that reason i don't like crowds and having to spend three hours in a store just to get what i need it pays off in the long run to get what you need early so that you don't have to go to different stores due to one store running out of things in stock.
I try to go early in the morning. We are usually up before 5:00am even on weekends and I discovered that if I can get to the store before 6:00am, it is ususally very uncrowded. For the Christmas meal shopping, I start picking up a few items begining in early December and leave only the perishable products to get the weekend before Christmas. This has worked really well for me over the years.