My wife attempted it this summer. To set the stage she was going from Supp Reserve to the Primary Reserve List to do summer "OJT/contact training" in the Chaplain Branch, ymmv depending on the branch/unit you are applying to. She is a QL5/PLQ qualified RMS clerk out less than 5 years (when she started).
She needed a medical, a PLAR, have an interview (as she was going from NCO to Officer), Security Clearance, Fitness Test. Started in Febuary, stopped in May as the process had not been completed prior to the summer training starting.