I can only offer our experience
You should ask your unit - our experience for the first summer training - 3rd class summer (VMI unit) was that it was exact, based on your hometown you ether went to east or west coast. My son's unit had acted like it was NOT up to MIDN which place - could receive opt out IF MIDN had conflict(like summer school) for the 1 session.
About this time - early 2nd semester -my son's unit contact was able to tell us general info - when my son told me I got the sense that the weeks were same general timeframe each summer, of course duration and overview were set. - 4 weeks, 1 in each subgroup - subs, avaition, surface, and marines - for all MIDN regardless if Marine or Navy scholarship
Our summer was:
For the east coast it was end of may to end of june, the 4 weeks MIDN were moved to other locations (for subs and marine). West Coast met in San Diego.
My son came to see that all the MIDN from his unit (school) were together as were each of the other college units. There were USNA guys there too, they were in seperate unit.
That was our experience, 2 summers ago.
YOUR UNIT MAY BE ONLY reliable source.
larrys mom