Oh thank you Op for confessing - me too! I had everything mentally sorted in November because I know that December is a busy time for us. But very little was ACTUALLY sorted. I had a folder of recipes printed from the internet. I had a couple of boxes on presents ordered online to post out to family and friends. I had a box of cards, and a list of what I was planning to buy for DH and the DCs. Then, suddenly, it was December and the cards were not written, the parcels not posted, the food order not done, the house is a mess etc etc. So yes, what you describe is me 
But I made a real effort at the weekend -
Food ordered online to come in 2 deliveries; this week for the store cupboard and the weekend for 'fresh' things.
Some stuff now prepped and frozen - mince pies, roasties, parsnips, stuffing
Cards and presents all posted out to friends and relatives in time for 2nd class delivery (just!!)
Ordered 'that thing' that I had been planning to buy for DH and DCs but had never actually pressed the 'buy' button
Mad dash around town at lunchtime yesterday for some odds and ends to pad out stockings a bit. Yes, probably a case of 'the twitch', but DC1s stocking looked a bit feeble when I put things in it; now much better thanks to Poundland / cheap stuff - bubble bath, selection box, colouring book
Had a blitz in the cupboards and took a boot-ful (!!!) of clothes to local charity. I've been meaning to Ebay them for about 2 years and haven't, so it is about time someone benefited from them
Tree is up and decorated, and DCs have been decorating the house with their artistic masterpieces
HOWEVER!
House is a tip still - needs a good clean and tidy before guests arrive, especially as MIL will offer to help the moment that she arrives if it looks in a state. Help always appreciated, but not on day 1!
Need to wrap presents for family and for stockings. Not a minor undertaking.....
Still a lot of cooking related work to do, although some of it may not happen. The trouble with printing out all those recipes is that I want to make them, but just how much will we actually eat?!
In my state of chuffed-ness about the food orders going in, I totally forgot to buy a turkey. Every other meal is planned and purchased, but somehow the blindingly obvious one passed me by
IF and only if I have time, I want to fix the paintwork in DC1s bedroom. We've had the paint for about 6 months and it will only take half an hour, but somehow it hasn't happened. Ditto cleaning the lounge carpet - I bought some stain remover weeks ago and it is still in the box (thank you <strong>betty</strong>). And less urgently, but still annoying, my car needs a clean!
I need to put the empty Christmas boxes back in the loft otherwise in-laws will not be able to get into their bedroom. Hmm. Maybe that should be further up the list