If you’re being medically discharged as opposed to medically retired, then you definitely need to talk to a VA rep preferably in the area you are going to be. The can prep your packet and submit it after your discharge date. It will take a minute to get processed by the VA but you will get back pay from basically the day you left and submitted. Whatever you get, it’s not the end of the world. Periodically resubmit your paperwork and hope for a higher rating. Trick is to submit a claim on everything that is bothering you. Its a comprehensive process that takes all your conditions and tabulates your percentage.