To avoid being woken up before 4am yet again I made a deal with my kids a few years ago: their stockings can ransacked whenever they wake up (some time between 2 and 4 in the morning, usually) but they cannot go downstairs to open their presents under the tree OR wake Mom and Dad up before 6am or their parents will be too tired and grumpy to deal with for the rest of the day. This arrangement has worked well over the past few years.
By the time I was a teenager my family had gotten into the habit of attending the early Christmas Eve mass and opening presents afterwards. My brood doesn't go to church but I still like the idea of opening presents on Christmas Eve, though we'll wait a few more years to initiate this because my boys will want to play with/watch/read every present, meaning that they wouldn't get to bed 'til dawn. Which sorta defeats the purpose of a calm, quiet present-opening session and a good night's sleep with a lie-in on Christmas morning.
Have we covered stupidest present/idea yet? Mine was buying my then 5-year-old daughter a bike and having to assemble it on Christmas Eve, with a missing bolt or two and instructions written in Cardassian. NEVER AGAIN.