Holiday schedule nightmare - Christmas is in 3 months and we haven't figured it out

Okay so the custody order says "alternate major holidays" but my ex and I have never actually agreed on what that means in practice. She thinks she should have Christmas morning because the kids are "always at mom's on Christmas" (which wasn't the case when we were married btw). I want to do an alternating year thing where I get odd years, she gets even years. We have a 4yo and an 8yo. I'm genuinely open to creative solutions here - split day, rotating times, whatever - but I need to figure this out NOW. What works for your families?