In Italy, as I was saying, also depends. Some open it on the night of the 24th (past midnight, in some cases). others, like my family, open them on the 25th, in the morning, which means that when I was a kid I spent the whole Christmas night awake. My sister and I, then, would "wake up" at 5 or 6 am to open the gifts (after waking up my parents as well). In retrospect, it must have been not so nice for them.

Now I spend Christmas eve at my gf's house, where a quite big gathering of relatives are, and presents are open after dinner, all together. very nice. Then, on the morning of the 25th, we get in the car and travel to my parents' house in the mountains, where we open other gifts in a smaller gathering. So, it is a mixture of both.