We took our little boy on his first trip when he was two (that was this past January; he'll be three in a week).
Honestly, I had wanted to wait. But his mother was set on him being able to go, so he went.
The verdict? A mixed bag. All in all, I'm glad we took him. He was actually great on the rides. He loved all of them, especially Pirates. To this day, he is fascinated with "the bones," as he calls them. I was actually a little surprised at the quantity of things he was able to ride, even though he wasn't tall enough for anything with a height restriction. I mean, I've been to WDW a lot over the last 10 years, but I had never paid much attention to what any child could ride.
He also really enjoyed our dinner at Chef Mickey's -- we all did.
On the other hand -- while he was fine with the rides, he seemed to think anything we happened to be doing was the greatest thing ever. Virtually every time we tried to shift gears and go do something else, he'd throw the worst tantrums I've seen him throw! Even when we had him strapped in his stroller, he'd kick and scream as if we were taking him to be killed. He'd throw anything he could reach, kick off his shoes, and anything else he could to disrupt progress. One afternoon, we had ADRs at Whispering Canyon. When it was time for us to be seated, he threw such a fit that my wife had to take him to the restroom and physically restrain him for 10 minutes until he calmed down. That was the worst one, but we had to deal with him throwing fits four or five times a day each day we were there.
Will he remember it? He does so far. He loves watching our video of SpectroMagic and Wishes. He loves hearing "the pirate song" enough to ask for it, and he often sings his own fractured-but-recognizable version of both that song and "It's a Small World." And we did get some priceless photos and memories.
However ... neither I nor (especially) his mother had as good a time as we normally would. Dealing with his tantrums was emotionally draining.
On balance, I'm glad we took him -- especially now that it's over! But I still think an ideal time -- I won't say the ideal time -- for a child's first trip is measured this way: When the child is old enough to walk onto Main Street, look down and see Cinderella Castle at the end of the street and realize, on his own and without being told, that he's in a special place -- that's an ideal time. I think that for very young children, everything is new, so it's a little harder for them to realize how unusual WDW really is. On the flip side, you want them to still be young enough to buy into what they see, so that it might stay magical to them for a lifetime.
But do I think there's such a thing as too young? Nope, not if you're ready to try it.
SSB