If you want to go to a computer school and don't want to get lost and quit in frustration. Learn C++ NOW! It's for your own best, and then you will also know if it is truly fun. 70% of your class will probably have programming experience too. I don't know about you, but I hate it when we discuss something in class I don't have a clue about. Also, coding in c++ gives you invaluable experience, and as far is I know, universities mostly focuses on theory.
Anyways, I highly recommend starting as soon as you can. Programming and especially C++ is a craftmanship and tool that takes more than a life time to master fully.
Becoming a programmer is a risk. But what is life without risks?
If you're a very bad programmer you are most likely not going to get any job anywhere. But if your are decent to good you can earn alot of money. But to increase your chances of that, start as early as you can.
(and while you're at it, learn as much math as you possibly can. And if you hate math, you just gotta learn to love it.)
This is all the answers I've gotten for browsing through questions on different forums.