It never fails. Something always happen to change your plans of a quiet and calm December. Whether it is unexpected guests or something you had forgotten, Christmas presents you have forgotten or plans that has to be moved around. There is always going to be something that will make you stressed. It happens to me every year. And even though I thought I had everything under control, I never really do. So I just take a deep breath, and try to do a little on my list every day, so I don't end up super stressed the last week before.
It is also important to take some time with those who matter to you and not spend all your time on completing the list too. So I thing you could always see if there is something you don't need to do, and leave it.