We went on our first Christmas Week trip last December. You can never start planning too early for a Disney trip any time of year, IMO. If I had let all the negative comments when I asked questions about that week get to me, we would have never gone. But, I was very aware of what the crowds would be like. I did my research on this website by looking at previous posts regarding Christmas week and reading post trip reviews. Don't hesitate to ask questions. There are lots of people on this site that have a wealth of information to share. My kids are 14 and 11 and we had the best trip of our lives, despite the crowds. We have gone every other year since 2007 so we've been plenty of times, just usually late May/Early June for Star Wars Weekends. But this trip was really special to all of us. We made our ADR's 6 months out and had no problems getting everything we wanted. The only thing we had a little issue with was getting the time for the Candlelight Processional we wanted. We got the Fast Passes we wanted. We had better luck with FOP and Slinky 3 days or more into our trip. And, while we were there, we used the refresh method and were able to get multiple fast passes for other rides after our first 3. We did EMH or rope drop most days, especially if we were at Magic Kingdom. Christmas morning at Magic Kingdom at 6am was amazing. We will never do morning EMH at Epcot again. Not sure if it was just a bad day, but something was going on with security that morning in the park and nobody got into the park on time. We used our FP that morning and headed back to Poly (our DVC home resort). We left the parks by noon or earlier most days (especially the ones opening extra early) and rode most everything we wanted to, some more than once. We had park hoppers and went to a different park in the evening. I used times guides from the previous year to plan our days for EMH and park hours, and for the most part they were right on. MK opened an hour earlier on Christmas morning, but that was a bonus for us. There were so few people in the park before 9am it was awesome. If Slinky Dog Dash is on your list of things to do and you can't get a FP, we found getting in line before the park closed to be the much better option over rope drop. We had a FP for Toy Story Mania first thing in the morning and when we got off that ride the Slinky line was already over 2 hours long. We got in line at night when the wait time was listed at 55 minutes. It only took about 35 minutes to get on the ride.
Maybe a little more info than you were asking for, but hope the info helps with your planning.