Why does puberty take so many years to start instead of just starting when you’re born, like growing in general? And how does your body “know” to start/stop puberty?

Question

I understand that puberty covers a plethora of stuff, but like, for example, why do you get a quick boost in height with puberty instead of growing at a consistent rate? Why don’t sex organs begin developing immediately when born? Why do women get their first period when they’re like 12 instead of as a baby? Why is there such hormonal turmoil during this period, rather than being drawn out from the beginning?

In: Biology