For me it's when I board the Magical Express. Greatest feeling in the world. It's like at that point I've entered the realm of WDW and have my whole vacation in front of me.
Several things ... The sight of my first palm tree when looking out the window of the plane after it lands at MCO
Once the hotel clerk says "Welcome Home", the packet of stuff along with the room keys is in my hand, and I'm pulling the kids and my wife away from the cartoons on the lobby TV to go up to our room.
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