This is such an irritating issue between myself and dh so I apologise in advance as I need somewhere to rant!
We have 3 children, every year we have the sane argument - no presents allowed to be opened until dh's parents get there! 
When they eventually do get to our house (they live 45 minutes away) I get given the order to make the coffees and breakfasts for everyone while they observe MY children opening the presents that I chose for them, I end up missing the majority of Christmas morning and it's upsetting because it only happens once a year and this year (again) I want to be selfish and spend Christmas morning with just me, dh and the dc's there.
This year it's going to be a tiny bit different as our youngest ds is just 5mths old, I'll be bf'ing him so that restricts how much I can join with dd and ds1 but at least I'll be able to watch their faces.
Ive repeatedly asked dh to ask his parents not to come until afterwards but he refuses each tine saying it isn't fair to them, and also his grandparents were always there on his Christmas morning so it's all he's used to I guess.
Ok rant over. Sorry 
Give yourselves a pat on the back if you read to the end :)