OK, to recap: OP
@AFVChic wants to make a
cash resie for a Boarwalk Grand Villa in September, and is hoping for either an annual passholder, Florida resident, or military discount. OP wondered if the first day of the trip makes a difference in how easy it is to get a reservation (Wed-Sun versus Sun-Thur).
I have never tried to book a BWV Grand Villa and I have never been to Disney in September so I cannot speak from personal experience.
I can say that pre-COVID, September was a popular time for BoardWalk because of Epcot's Food and Wine Festival. People liked to be able to walk to and from Epcot. Getting a BWV room in September was more difficult than at other times of the year.
I also can say that the latest edition of the Disney Files Magazine for DVC members has a one-page article about getting cash reservations. It says:
a) The company owns some inventory, including yet-to-be-sold inventory at new resorts, which is available for cash reservations.
b) Sometimes a member uses their DVC points for something other than a stay in a DVC resort. For example, a member uses their DVC points to book a
Disney cruise. Those points are converted into hotel inventory which can be made available for cash reservations.
c) Sometimes there is availability within 60 days of check-in. Those accommodations can be made available for cash reservations.
d) "It's worth nothing that we carefully restrict the rental of accommodations with particularly high Member demand and low inventory. Most Grand VIllas, for example, are typically available exclusively to Members, and at The Villas at Disney's Grand Californian Hotel & Spa, we don't currently rent any of our villas to guests."
There are people on this thread who will be able to address OP's question better than I can.