Generally, people send Christmas cards between Thanksgiving and Christmas Day. Remember that the mail system gets busier the closer it is to Christmas. If you want to make sure your Christmas card arrives on time, send it earlier rather than later. Sending out your Christmas card a couple weeks before Christmas should ensure it arrives on time. Some handmade Christmas cards require hand-canceling at the post office due to their thickness, so you may want to allow a few extra days for this process.