No, there are no guarantees for ME. The current waiting list is 18-24 months with approximately 250+ people on the waiting list. You would go to boot camp, report to your first unit as a non-rate, put your name on the A School list after the required amount of time (4-6 months) then when your number comes up, off you go. That is assuming you are going active duty and not reserve. Reserve is a horse of another color and slightly different rules apply.
