-Gather ALL of your medical records.
-Look up "disqualifying conditions for the military" online.
-If you have disqualifying conditions, you will either need more documentation, letters from your physicians and/or a waiver from the surgeon general. All of this has to happen before MEPS will let you come.
-Start talking to your recruiter. From my experience, they won't really let you get started with anything yet, because they're still working with the apps for the current cycle. But, try to find out how early you can start doing your medical stuff. As I said, I've been waiting for 4-5 months now. It's a really sucky reason to lose a scholarship.
-Lastly, Take your DAT if you haven't. They will probably want all of your dental school app stuff completed before they talk to you. They don't want to waste their time if they don't think you're actually qualified.