Just be careful of lines that may form before you get there. I had always heard that someone would be at a gate to the left at the MK and would check your ADR in order to let you enter early. When we went two years ago we had early ADR's at the castle and arrived at the gate 30 minutes before our ADR. There were already two long lines of at least 100 people each and no one was being let in. The front of these lines were mostly tour groups that looked like they had been there for a long time. Many of the kids were spread out on the ground and had a chain type thing going where they sleeping on each other. We told a CM that we had an early ADR but they just directed us to the back of those long lines. They starting letting people in at the time of our ADR but we of course had to wait for all of those kids to rouse, get their stuff together and go through the turnstyle. No one was checking any of us in order to see if we had an early ADR. We were about 15 minutes late to breakfast at the castle but it was OK because everyone else was late. I was just disappointed because instead of a sprint, I had imagined a nice slow walk in a fairly empty park to the castle. I still wonder if all of those in the tour groups also had an early breakfast because they certainly didn't appear to heading anywhere once they entered.