I meal plan for December as a whole rather than week by week which is my usual method.
I have loved planning Christmas, ever since we were married several decades ago. I always meal plan, hadn't ever thought of doing a whole month, I think that's a great idea. What I have done for years is avoid our usual Sunday roasts throughout December,, to help us appreciate the 'roast of the year' more. As we eat out a lot in December with friendship/hobby:work groups, I do focus on simpler, lighter foods for family meals.
I love cooking and collect recipes from the weekend magazines or links to online recipes I've stumbled across, often on MN. I keep a look out for recipes which would be good for the festive season - from simple but different family meals to ideas for NYE or other entertaining. I used to buy all the Christmas magazines but increasingly found them repetitive and a waste of money. I now prefer to buy Christmas books, often from charity shops, and love spending a few evenings looking through them on a cold November/December evening to help with my planning.
I try to buy cards, wrap and ribbon in the sales and put in the loft when I put the decorations away. Saves money but more importantly saves time and the cards are there if I am bored in Novemeber and want to start writing them. Ditto paper if I decide to 'wrap as I buy'
I keep various Christmas checklists to refer to each year, they are tweaked and updated each year but lots of the things are common to every Christmas, so it doesn't make sense to start from scratch each year.
Eg non- food items (eg table cloth, serviettes, candles, crackers, cards, wrapping paper, ribbon, sellophane, sellotape,gift bags etc).
Christmas Dinner components
Snacks - nuts, crisps, dips, crumpets, mince pies, Stollen, Christmas cake etc)
Household/kitchen staples to be sure I have plenty of for the duration (toilet roll, kitchen roll, dishwasher tablets, laundry detergent, tea, coffee, milk, cereal, store cupboard items such as beans, tinned tomatoes etc)
I don't actively buy presents til later in the year but I do listen out for ideas throughout the year and make a note on my phone. Eg DH really enjoyed a specific wine at a restaurant at the weekend, made a note of it (as he's a nightmare to buy for so any little thing I know he'd like gets added to the list.
We are a family who love our Christmas stockings, even for adults. It gets harder each year to think of different things that will be useful or enjoyed so I look out for ideas all year round and keep a note on my phone , even if I don't buy til later in the year. (For anyone else who does adult stockings, I started a thread here )
This all makes me sound like a bit of a saddo. I honestly have a very busy, varied and fulfilling life. I just love Christmas and am an avid planner!