I heard
MNSSHP tickets went on sale. In my experience, the official announcement with dates and pricing for Military Discount tickets has usually appeared approx May 1st. The Military dates will be in September, but 2-3 years ago (as I recall) Disney extended the offer into the first week of October. This extension was announced at a later date (around Sept). I would keep watching the militarydisneytips.com website for info.
For the MNSSHP Military Discount dates, Disney allows active Military members and retirees (or spouses) to purchase their allotment of tickets
even if the MNSSHP party is sold out. Last year we did just that for a sold-out late Sept date. We went to the ticket booth at the TTC with proper ID and purchased Military Discount tickets for that evening's party. (Too bad it rained Cats & Dogs, but that's another story.)
I'm not sure if Shades of Green sells the MNSSHP tickets. We've always purchased them at the MK gate, or at the TTC or DTD. (Any WDW ticket booth should handle this purchase.) Pretty sure these party tickets aren't sold on base.
http://www.militarydisneytips.com/Military-Discounts/Theme-Park-Tickets.html