Daniel started using "I" instead of "Daniel" or "Dan"( 29 months)

I realize that I am supposed to know the age range that children start using the personal pronoun "I." I have known this. I know which book I read it in during graduate school. Doesn't matter because the reason I care right now is because "Dan" is finally using it! He's been using it for about three days. The first time was during a conversation about some horses that when we drive into Chapel Hill. We were on our way to a yard sale on Saturday. We were talking about items we find at the yard sale. We passed the horses, and Daniel said, "Hi horses! We going to yard sale!" He went on to say that the horses might need a hay blanket. I said something like we might find a blanket at the yard sale, but it probably wouldn't be big enough for a horse. Daniel said something back to me that I couldn't understand. I had to ask him to repeat it three times. I finally got it. "I horse, Daniel would use it." (If I were a horse, I would use (the blanket from the yard sale.) I thought that was a pretty cool way to start using "I." Since then he's used it several times, although he still uses "Daniel" and "Dan" some.
I'm waiting for him to assimilate "I" into his most famous and frequent line these days. "Dan toooolllll (tell) you." He says that with a very serious expression in response to my query, "Do you need to go to the potty?"