Like many others, I budget for Christmas throughout the year. I don't set aside a particular $ amount each month or paycheck or anything, I just know that a chunk of change will be spent on it throughout the year, and I subtract that amount from what my savings are for the year. Not exactly how others do it, but it works.
I've actually already spent the biggest chunk of my budget for this year - I typically buy plane tickets for Xmas a day or two after the booking window opens in January. While not smart most times of the year, I find I usually get the cheapest rates on Christmas tickets this way. One year it backfired on me when they dropped ticket prices closer to Christmas, but all other years it's been a good move.
In addition to gifts and plane tickets, I also budget for: stocking stuffers (I spend a fortune on those - they need to be budgeted for! LOL), Christmas tree/other decorations, Christmas activities (we like to go see a Christmas movie in theaters, etc.), other expenses related to travel (car rental, parking, cat boarding, checked baggage, outrageously priced airport meals), Christmas cards and postage, new Christmas outfit for DD and extra "tips" for the gardener and my hair stylist.
I admit I already have a few gifts bought: a camera and some wireless headphones for DD (got both as great deals), and a book for a family friend. While I used to buy like crazy throughout the year, I found that I ALSO went crazy closer to Christmas on those last minute wants that DD came up with, or all the great deals that come out. So I've learned to limit my buying for DD (the bulk of my gifting) until closer to the holiday. Gifts for people like my mother, siblings or friends I will pick up throughout the year as I see something that catches my fancy, if it really seems perfect for them. Otherwise I wait until closer to the holiday too.