Start practicing now. The goal is to have it ready for the week before Christmas. I am not too happy selling beginner Christmas music on Christmas Eve as a gift. Seriously, who wants to practice Christmas Day? It should be polished and ready to perform.
Choose Christmas music that is easier than your method book, so you can learn several tunes each week. Having six songs at performance level in your repertoire is so much more fun than one more difficult piece that you can barely get through!
Look ahead, yes, turn the page! Try the next piece in the book. This is the best sight reading you will do all year. That also means BUY the book! A single photocopied page is not acceptable (and it may be illegal). Think about it: is there any other music you will play year after year? Isn't it worth it?