I was only thinking like a year in advance. Babies aren't very exciting... there's really no way they can be. The intellegence thing is cool, but it needs to progress. Being two years old isn't bad, you can walk, talk more effectively, and still get carried if your wittle feets get tiwed...
As far as the regressing back and forth, you have to remember, this is Naruto universe. Really... anything is possible. But of course, you have to be a certain age before learning that spell...