I was about 22/23 when I first found out my MBTI type. At that point, I had two decades and change worth of living that I could look back at and start to determine how my life up to that point fit in with what my "type" was suppose to be like. Also at that point there wasn't nearly the flood of information both supported or unsupported about personality and temperment as there is now. I didn't go back to college until I was 28 and then I truly studied psychology and particularly personality. My point is I had some time behind me when I seriously started contemplating personality....and what that meant for me.
My question to you all is..What do you all think the age at which your type is determined has to do with your development. Is knowing what your type is suppose to be lead you one way or another?