Christmas Day split with the ex - who gets the morning?

Separated 18 months. Our daughter is 6. Last year was the first Christmas apart and her mum had her all day, I had Boxing Day. It was fine for my daughter but I spent the day on my own and it was grim.

This year I want to suggest alternating Christmas mornings. Her mum will say it's unsettling to move a kid halfway through the day.

What do other separated dads do? And how did you bring it up without it becoming a fight?