One of the best times to stock up on sale items is after Christmas. Most stores have items marked down, especially Christmas items. It is a great time to stock up on wrapping paper and other decorations for next year at a fraction of the regular price. Also, you can start finding gift ideas for holidays and birthdays throughout the year. If you can find wrapping paper that is not necessarily Christmas themed you can use it for birthdays, etc throughout the year.
Also, if you get in the habit of putting some extra money away each month and designate it for next year's holiday expenses it can take some of the burden off of you next Holiday season.