So depending on what you read, your dominant function develops from 0-7to13, your secondary from 13-20, your tertiary from 30-40 and your inferior from 40+
This seems a little slow to me. So, within my experience and analysis, when a function first starts to develop in earnest it tends to experience a growth spurt whereby the function experiences exaggerated use for a while until the person becomes more used to the change and things balance out. This is clearly reflected in my own experience.
Up until the age of 10 I had basically no filter and no sense of self-conscience or embarrassment. I wasn't quite captain wildchild, but I remember when my mom would talk to other adults I would want to join in as part of the conversation, etc. I made friends easily because I had zero qualms with strangers. It was right around 9/10 that I experienced my Fi growth spurt where I started to become very sensitive to my internal sense of morals, and much more self conscious / self reflective- little things my friends would say I would be overly-sensitive about (from an ENFP perspective, some INFPs might find this their normal), however this was over by around 14. Then around 17-23 I went through my Te growth spurt, and you can easily see this reflected through my posts on this very forum, in fact I may still be on the tail end of it. My Si is still quite weak and requires conscious will-power, though it gets about 2% easier each year, I still haven't had that game-changing surge yet.
Sub-consciously that may be what I'm waiting for before settling down, but that's a whole different tangent of a topic.. anyway..
I want to know when you've experienced each respective growth spurt and development, and your reflections on the topic.