We got him a potty chair a few months ago because he started staying dry through the night. He liked it and I set him on it in the morning and he went a few times, but only first thing in the morning and only when I asked if he wanted to. Eventually he lost interest so it just sat in the bathroom and I didn't push it.
Friday, out of the blue, he goes "Boppy!" I didn't know what he was saying at first because that's not the term we use. So I said "show me" and he walked into the bathroom and started to sit on the potty chair. I took his diaper off, and he just sat there and drove his hot wheels car on his legs. Then he started getting up, so I was going to put his diaper back on, but my sister-in-law came to the door because her car wouldn't start. I was talking to her, and K came out of the bathroom going "YAAAAAY!" I checked and he had done it!
Tonight he did it again! He's wearing "big boy pants" over his diaper now, which is the coolest thing in the world to him. He is all about "big boy" stuff right now. He likes to sleep in his big boy bed (which is actually a crib, hahaha), and he likes to drink out of a cup without a sippy lid. Man, it would be nice to get him out of diapers before the new baby comes, but I don't want to push him.