OK so you are on leave. When you ETS do you have to come back and take care of all the paperwork in person and in uniform? When I ETSed I walked around post for a week getting paperwork signed, signing paperwork, changing the ID cards from company level to battalion level, all in uniform. If you can do all that in Civies then I really wouldn't worry too much about it. Even if you have to do it in uniform, you are ETSing so I doubt too many people would have a lot to say with non regulation length hair especially since you have been on terminal leave for that long. But like Jessica said, make sure.