Always - although if we are "down home" (ie visiting DMIL and DPs), we end up having Christmas Lunch (turkey dinner) and Christmas Dinner (turkey dinner) to keep both happy.
When we stay "at home", in our own house, we always eat in the evening. Somewhere around 5-7pm - depending on when the bird is cooked and we are organized.
So up whenever DD wakes, open stocking, relaxed breakfast, tidy up, showers etc.
Out for mass - we usually aim for 10.30 as that's family mass (kids wandering everywhere, Priest invites them up to the altar etc). But occasionally it's been 12. (At home, its either "Midnight" (7pm) the night before, or 8.30am).
From there, we have just one call to do nowadays - it used to be 3 different sets of extended family to visit local to us for a drink, a mince pie and a chat. We used to call into home between visits 2 and 3 to get the turkey in the oven (it was on our route), as it meant we didn't have to rush that last one.
But home, get the oven hot (if we've forgotten to set the timer to heat it).
Get the bird into the oven. Throw in a sheet of M&S nibbly things at the same time.
1 person will get the rest of the kitchen vaguely organized. While the other lights the fire, turns on tree lights and Christmas music, opens the bottle of bubbles etc. DD wanders around, sometimes being useful.
Once nibbles cooked, bubbles open and order put to the chaos, we go into the sitting room with our snacks to open presents. This is a relaxed time, it may involve occasional breaks to check the bird or get the potatoes on etc.
We kind of potter around getting the rest of the meal organized, sitting down to chat, clearing up the wrapping paper, setting the table etc.
Then we eat.
Then we clear up, and fall on the sofa groaning. Maybe watch a movie or something, if anything catches our fancy, or else just relax and chat. And head to bed at a reasonable hour because we are hosting people next day (well, I usually strip the turkey and put the stock pot together but don't turn it on, and might get a few other bits started before bed - if I have the energy).