Most people don't know that many Christmas trees are already cut by mid-November but are not purchased until after Thanksgiving. You are just as well off to buy the tree early and prepare it for optimum freshness over the rest of the season. You should not consider yourself getting a fresher tree by purchasing later.
Also, every year is different when it comes to Christmas tree availability. Christmas tree production can vary annually. Some years have less shopping days between Thanksgiving and Christmas. Tree sellers will be busy over a shorter period of time and you will not have as many days to shop for a Christmas tree.
Natural disruptions (insects, disease, fire, drought or ice) can cause regional Christmas tree shortages which can make certain Christmas tree species hard to find. In any event, buyers need to plan and purchase early to pick from the best holiday trees on the lot.