Start speaking with an AMEDD recruiter now so you know what documentation to get together. The application process is long and tedious. As the Sir mentioned above, the board meets once a year. There is also an interview process. It took my recruiter about 1.5 years to get my packet squared away. Of course, he had a hard time locating his glutes with both hands. You also have to be persistent and squeaky clean. Commissioning is an honor not an entitlement. Essentially the Army is hiring you for the job.

You may have been given some incorrect information. Your enlisted time in th ARNG will only help you from a retirement point of view. It will not help your rank as an officer. To come in as a direct commission officer, you will need to put together a packet with a medical recruiter. Those packets are boarded once a year and the selection process is highly competitive to enter as a physical therapist on active duty (many applicants and few slots at this time). It is also very competitive to enter the USAR as a PT. Your rank will be based on your degree and years of experience as a physical therapist. I suspect you are looking at 1LT as a new graduate. I am unaware of a program that makes you a CPT upon graduation from BOLC. Best wishes!