See my summary of GV availabilty at 7 months out during the year here:
https://www.disboards.com/threads/grand-villa-availability-at-all-resorts.3564854/
As to May 2017 at 7 months out at WDW, and excluding OKW and your home resort AKV, which you should book at 11 months out, the following was the availability:
SSR and VGF were open the entire month.
BWV, missing couple days early May but actually open for May 4-13 until October 11 when some of those days filled. For May 14 to 31,missing 3 to 4 days for any given 7 day week with any start date after May 13.
BLT: Early May Theme Park (TP) view GV open but Lake View (LV ) missing two nights. Both open week of May 7-13 until October 12 when some of those days filled. Week of May 13-20 LV GV open, TP GV missing two nights. May 20 to May 31, both missing Memorial Day weekend.
Note that new CCV will also be open and could have availability.