Christmas eve
DH and I have been married 2ish years, together a year longer. This is the first Christmas that we've had SD on any of the "Christmas" days (ie: 24, 25, 26). Usually we get her sometime around the 28-29. It's been a while since I've posted, so I'll just state for the record that there is no CO.
In the past, I was very vocal about DH's rights as a father, and I pointed out several times that he should be able to have her for Christmas. He generally doesn't want to rock the boat though, so goes with what BM decides. Whatever. I'm not going to fight about it. I have bigger fish to fry.
Anyway, we have her until tomorrow evening! So excited 
We are going to be 1/2 hour away from BM's house, and she agreed that we could have her until after dinner. She even agreed to pick her up! This is a miracle because DH does ALL of the driving, and we live 2 hours away without the snow. It took DH 3 hours to pick up SD yesterday because the roads were crap. Fast forward to now. BM asks where we're going for dinner tomorrow. DH says that it's with my family. Now, she wants to pick SD up before dinner. They went around and around for a bit, but nothing got resolved. At this point, I feel like we should text BM with the address 1/2 hour before dinner is over. We won't, but that's what I feel like doing (so please don't flame me for that fleeting thought).
There's really no question/advice seeking. I just felt the need to vent a little.
Re: Christmas eve
As for now, technically he has just as much right to the kid as the mother does. Neither one has legal 'custody' until its spelled out in a CO. He can keep her as long as he wants legally, but he shouldbe prepared for backlash from BM.
DH is military, and is away a lot. Anyone have any experience with those kind of COs? Do they look any different from regular ones? What happens if he's away one Christmas? Does he get the next year even though technically it's not his year? Any input would be great for future reference. Thanks!
From a BM perspective I understand stand why she's upset your h and his family hasn't seen LO for holidays in 2 years. If I sent my LO to be with her father for Xmas I would hope he would spend it with his family so they could spend time with LO as well.
But if I were you guys I'd keep LO until after dinner, BM shouldn't go back on her word.
I didn't say his family hasn't seen her in two years. MIL and BM are friends, and live 2 minutes from each other. They hang out all the time. MIL cut us off over a year ago, so we're not seeing his family. It's a bit complicated, but it's mainly because we stood up for ourselves. BM is taking SD there sometime in the next few days.
Also, we've never had Christmas because she didn't want to give us Christmas. It didn't fit with her plans.
She has to work tomorrow, which is why we have her without a fight.
ETA: I do understand your pov though
BFP #1 11/07/2012 EDD 07/09/2013 M/C 11/22/2012
BFP #2 02/05/2013 EDD 09/19/2013 Arrived via c-section 09/27/2013
You could set it up so that he has every other Christmas/thanksgiving/ect. and just specify that if the parent who's holiday it is is unavailable to be with the child the other parent gets her.