I agree with several of the previous posters that maturity is probably one of the main things to consider.
I applied to Eurocontrol at age 17, was admitted and started just after my 18th birthday. Looking back on it I was absolutely too immature back then. I'm one of the unfortunate ones who failed during training, though I was very keen to become an ATCO. And maturity had a good deal to do with that failure. I will of course never know for certain if I would have succeeded had I waited a few years and gotten a degree first. But I am sure that some more "life experience" would have helped a lot.
Of course it may be different for you; you're the only one who can decide about that I'm afraid!
Anyway, whatever your choice will be, make sure to go for it for the full 100% and more. Good luck!