Yes, USAA will take care of this. Once they are notified your child is at an Academy, they put them in a special category since they know they are not authorized vehicles yet and will not be home much. Essentially, they are covered as an occasional driver for no charge until there 1/c year when they are authorized a vehicle, then the regular insurance charge kicks in again. It's a very good deal. Don't drop her from your policy, just put her in academy status and enjoy the reduced premiums.
Side note, USAA does a very cheap renters policy for academy kids as well that covers all military uniforms at 100% if they are lost etc. I think they have laptop insurance too. If I remember right the whole thing was like $55 a year to cover military gear and the laptop. Again, a very good deal. USAA is set up to handle academy kids. NFCU and others are competitive, so it may be worth it to shop around.
With USAA often the first step is for the cadet to log on and change there profile to active duty - military academy. You may have to call or fax the appointment letter to prove eligibility.