How do you do holidays while co parenting?

How do you do Santa and Advent calendars? We are on day 5 of the month and forgot to pull out her calendar, but she also goes to her dad next weekend and then on the 20th, so would you just have them finish it up before leaving? When they get back? And does Santa only visit the household that she is staying Christmas Eve at? Her dad and I are trying to figure out how we want to do the Santa thing. Especially since when she spends it with his side, his mom is big into Santa magic being real.