Need help! Which route should I take?

I am 15 (have time to think) but I wanted some help on which route I should take, I know what career I want, a Sheriffs Deputy here in Ellis County. But I don't know if I should go join the Army when I am 18 and then become a Deputy or become a Jailer for the Sheriff's Office until I can become a Deputy. IDK both sound good to me.