You sound like a wonderful friend, you should be proud of that
Personally, to avoid the the stress, i buy early in the season, or online so i don't have to be around crowds. Making some decorations helps too, little things for the tree, or your friends tree, hand sewn, i think it always feels amazing
What else, i like to plan and make lists, of what to buy or make and when, so it's less to rush up on me in the last fortnight