It seems that your first function is pretty strong from the get-go. Your second function works fairly well in your youth and seems to fully develop sometime in the teens (or at whatever point you decide to make good use of it). Is there a timeline any of the older folks have with respect to the third and fourth functions and their development? I'm approaching my mid twenties and it seems that I'm getting more of a handle on my third function, but the fourth is still a hell of a chore for me. I will probably igore my third function on a regular basis, but I seem able to use it in the situations when it is needed (although it is rather raw). If I could do the same with the fourth, I would probably have a potentially better handle on more difficult life situations.

It seems with regard to the unconsicous functions, they develop through exposure to things of that specific function's nature, but they are course sporadic, and hard to predict when their use will arise. They lack the constincey of the conscuious fucntions.

The MBTI articles address this point, but they are only to be looked at with a skeptical eye as they are, well, MBTI articles.