We don't have a routine. Not for DH & I. This year will be the first year in who knows how long that we will open our gifts to each other on Christmas Day. We bought a house this year, so money for traveling. Although, we will be having Christmas with my parents on like the 20th, because they will be here the 15th-22nd.
It's a byproduct of our travel schedule. We are either with my parents, in which case Christmas is on Christmas Day. Or we are with DH's parents. Which means we have Christmas with them on Christmas Eve morning, or sometimes the day before. Christmas Eve is with DH's Grammy, Christmas Day is with DH's Grandpa. On years we aren't with my parents, it's hit or miss if their box will arrive before or after we leave for DH's family. We will either open them when DH & I are doing our Christmas prior to leaving, or we open them when we get home. My birthday is the 21st, so we try to avoid opening any Christmas presents on that day, but it doesn't always work out. Last year, I got to open presents every day for a week!