You should be in great physical shape. Being a good shot will get you to sniper school but that alone won't get you through it.
Plus, anyone can hit anything with a .22. Move to a higher caliber and try hitting longer ranged targets.
And I'm not sure how the Canadian military will have this but I don't think there is a way you can be in armor and then become a sniper unless you changed your MOS to infantry or another MOS that supports snipers. The military will only send you to a school if they feel you should go. They're not going to send you there just because you want to go.