I don't think I would start now, before Xmas, but obviously it depends on what kind of a Xmas you are thinking of having. Ditto new year. This is one diet that you really can't dabble in and out of, and you need to get your head in the right place first. There is a lot to relearn about eating, and the planning pays off, I think, particularly in making sure you have the right stuff in the cupboard/fridge to avoid temptations!
It took me 3 or 4 weeks to work out how I was going to adapt my meals etc, and my actual start date is a bit of a guess really because I was 'thinking' myself into the diet for about 10 days or so before hand. I'd done attack, and launched into cruise before I knew it! Probably just as well - I may have found an excuse not to start otherwise.
I wouldn't recommend my method - better to fix a date, not too far away, plan for it, and stick to it. Good luck whatever you decide!