Congrats on being both lucky and wise enough to be able to do this at such a young age!
I would currently advise against GICs at all unless you're getting really good rates. If you're willing to bounce your money around, you can get ~5.5% (give or take 0.5% or so) in savings accounts on new deposits. Tangerine and BMO for example have rotating promotions that you can sometimes take advantage of around those rates, and your money isn't locked away.
If you don't feel like moving your money around as much, some online banks are offering ~4% interest rates on their savings accounts, and your money isn't locked in. I think some even offer TFSAs for those, if that's what you're after.
imo, you probably don't need GICs. After they mature or whatever (you get the money because they term is done), see if there are better places to put your money.