For time between mid-Jan and mid-Sep, SSR, Kidani savanna view, and Riviera GVs are usually open at 7 months out (although Riviera has not been around long enough to define a real pattern), and SSR and Kidani savanna view may still open at 6 months out. During that time, you can also often get BLT, Kidani standard view, and even VGF at 7 months out but there also a number of times when those are full and there are no definite dates from year to year for that, and at six months it is much more difficult, so likely you should avoid those, and any time around Memorial Day would be more unlikely. OKW is the one least likely to be open but even it has chances at times such as in July after July 6 (one of
DVC's lowest demand times of the year).
If late Sep through marathon weekend in Jan, DVC's fall high demand season, best chance is for SSR but even those GVs may fill before 7 months out for the extremely high demand times during that fall season, particularly for time during the Christmas week, first two weeks of Dec, Thanksgiving week, and the Nov and Jan race weekends. Kidani savanna view and Riviera are also open for a week some of the times outside of those extremely high demand times but chances are less than getting SSR. moreover at 6 months out chances are much less likely for anything. As to any other GVs, you should assume it will most often be difficult to get a GV at 7 months out during that fall high demand season.
Note, what I am not clear on is why having the December use year means you have to wait until 6 months out to reserve time in late May or early June 2023. You could go online at 11-months out and book home resort using banked Dec 2021 points, Dec 2022 points and borrow 50% of your Dec 2023 points. You can go online in Oct/November 2022 at 7 months out and reserve late May/early June time using banked Dec 2021 points (as long as you bank them by July 31, 2022), Dec 2022 points, and borrow up to 50% of Dec 2023 points, i.e., the applicable use year points you can use in Oct/Nov to reserve May/June are the same as the points you could use if you waited until December to make the reservation.