Christmas Day, of course! Satan...uh, I mean, Santa doesn't come until Christmas Eve, while we're all asleep (and wearing our tinfoil hats). So the prezzies aren't there to be opened until Christmas Day anyway.
Christmas day. I know a lot of people who open their pressies on Christmas Eve though. It is very common in families where the parents have divorced and remarried for example since the kids go to one parent on the Eve and the other on the Day.
I normally open any present from my friends as soon as I get them though because, usually, they are not the kind of things I would want to open infront of my parents on Christmas Day
We open our presents when ever we can. We have worked the last 2 Christmas soooo. Plus throughout the year, we get each other things. Christmas throughout the year.