Some of my friends say it's too late to start then??

I probably start studying Aerospace engineering when i reach 21, but my friends say that it's oo late then and you should start when you're 19 or 18. well i can't start now(i'm 19) and have to wait almost 2 years. they say it's better if i study something else which will only take 2-3 years to study...... but i wanna study aerospace engineering. it's not actually late when i'm 21 right? i know i have to study for many years to become an engineer(but it's what i like).