OMPF file and what I need for an appointment

I will be visiting the St Louis facility in the fall. I have at least 3 specific file types that I will be wanting. First one is for a OMPF Navy file from the Korean War. Since the records are OPEN 62 years after-- would I need a DC for him? Should I complete the SF 180 online with my request for an appointment? I have his DD214 already, but I want to see and copy of his service file. How far in advance should I request an appointment for the records? Will make separate questions for the others I need.