My CC's letter unfortunately said he wanted to "retain" me after my UC/MEB. I've already done 20+ years and would prefer to focus on my health. So, now C&P exams are complete and waiting on NARSUM etc. Crossing fingers for unfit and 50% VA.
IDES you file for your VA benefits while in the military. You'll know your rating before separation. Legacy you file through the VA after your separation date. I think most people do the IDES so you get your disability and retirement pay as soon as you get out.