It really does need to come from leadership. The last 2 places I've worked had basically no work after Thanksgiving and much of leadership did take off basically entire month of December.

Also we recently started having an occasionally Friday that everyone takes off same time. You don't have too but to make it easier that people who are often quite busy have an opportunity to not feel like things are getting behind. Over 90% participation(100+ people) in our group mental health day.