We were there from 11/28 through 12/6. We did four 3-4 hour tours of MK in that time. All before noon. Each time we went there were minimal waits. The lines of course got longer by noon. We hit Fantasy Land first for the kids. Generally, for all of our trips arriving at or near opening time, everything was a walk-on. Later towards noon you needed a fast-pass and some planning, but waits were around 5 minutes if you timed it right.
There is much to be said for getting to the park early. Normally we avoid commado-park tactics with small children in tow. We planned our trips around our estimates on our children's endurance. Since the weather was cool, we carried a single bottle of water for the children, same basic essentials and had a plan of rides to hit in sequence. Following our plan, we almost always walked onto WTP, IASW, PP, SWSA and right into the Philharmagic every time, never a wait > 3 minutes for the latter.
The kids never seemed to tire out, but it's been 14 months since the last visit so apparently they can handle more. We made the afternoon our resort-time and enjoyed the surroundings. We stayed at the Polynesian so it was always a quick hop over and back. We did a lot of character meals so we never wasted time standing in the parks chasing down characters. It got to the point where I whispered to my wife that the next time I saw Donald Duck I wanted it to be with orange sauce. Sadly "Chef Mickey" didn't prepare any in advance. Joking of course, however I do highly recommend the character meals. Especially "Chef Mickey" and save yourself some time chasing down the characters in the park.