Sounds like you're off to an awesome start then. Keep it up! There will be SEVERAL times during this process where you will be anxious, want answers, frustrated, pissed off, tired, etc. But in the end it is all worth it.....
If you go into the 1001 questions about the ASTB thread, I believe its on page 36, myself and DukeAndrewJ both posted all the materials we used to study for the ASTB. Take advantage of that as well. We were both Pro-Rec'd in August together.
The status of the person doesn't matter much, I mean it does, but in the grand scheme of things it doesnt. What matters is you get someone who KNOWS YOU and speak about your different qualities that you possess and why that is going to make you a stud if the board choose to accept you to become an officer.
I had my Fraternity's International President and CEO, My Graduate School Advisor/Former Astronaut & Professor, A friend of mine who's known me for 14 years, a skydiving friend of mine who is also a lawyer, my Fraternity's Regional President, & my cousin who is in the Air Force. All of those combined spoke about something different, from leadership, to people skills, to management skills, to work ethic and physical attributes, etc.
The point is, they all knew me well enough to write about me and tell the board why I'd be an asset. Lastly, I also did an interview with my NRD's OPO who is a former NFO along with our CO. That's not necessary but it also doesn't hurt. I had been going through this process since last February, so when August rolled around, everyone in the office knows who I am.
Anyways, get your LORs from whomever you feel qualified to speak on your behalf about YOU. Your high school principle isn't a bad idea, but unless you live next door to them, I'd say go for someone else if you can. But if you have no other ideas or people to do it, then use it. Just keep trudging bro and working at this piece by piece. You'll need that spirit, drive, and motivation when you get to do MEPS and start filling out the SF-86