Joining the air force when I am 18?

I will be turning 17 soon and would like to join a branch of the military; preferably the air force. How hard and how long will it take to actually go through the application process and gry accepted? uming that I have no criminal back ground add will hold a diploma. Also my plan is to do 4 year enlistment , get a two year degree while in, then finish when it is up. Then go to dental school and come back as an officer in the air force. Does this sound like a good plan? Also do I or can I go to MEPS before I am 18 if I get accepted?