Hi Samantha,
I was 28 when I finished my PhD, but I think that you start being a scientist when you start your first research.
That was the research for my master's thesis, and I was 23.
When you're in high school you think that everything takes forever.
The older you get, the faster time seems to go.. When you go to college and university, time flies.
Including kindergarten, I have been to school for 24 years. It was totally worth it! As a scientist you keep learning forever.
Mandy