This response is provided based on the information you shared and should not be used as the sole source for making a decision. You should seek guidance from the chain of command, IG, JAG or other certified agencies before making any decisions. How you chose to use this information is totally up to you and is your sole responsibility.
The rating period starts the month after your previous NCOER ended. For example:
If your previous report ended in April your next reporting date would start 1 May
The initial counseling while required by the regulation to be given or should be given within the first 30 days does not have anything to do with when the next rating period starts.
If I understand your correctly you are being rated for All of May, all of June, all of July, and a portion of August. I would then say the NCOER meets the 90 day requirement…if in fact it was 90 rated days.