Join military before, after, or during college?

I'm pretty interested in the air force. I definitely want to go to college. Now I don't know how serious I am with the military for how long I want to be in. I can't decide if I should do air national guard (reserves) while I am in college, or go to college and then start a career in the air force. How will I know if I will like the air force? I don't think I would like ac because I'm very indecisive and would be scared I would change my mind about joining while in college.