The home resort booking window opens for online registration at 8 a.m. eastern exacty 11 months out from day of arrival. MS and the phone lines do not open for taking reservations until 9 a.m. and for some rooms at some of the resorts that can be too late to get the room.
At exactly 11 months out from arrival date, you can book up to seven nights at your home resort. The original reservation rule that was in place for many years actually required you to book 11-months out from your day of departure from WDW, but that was changed years ago. Note if you need more than 7 nights, you can book 7 nights exactly 11 months out, and then add days thereafter by modifying your reservation online or via contacting MS.
There are a number of rooms that tend to disappear at exactly 8 a.m. at 11-months out, but as a BCV owner you will rarely have that issue. BCV studios have sometimes disappeared at exactly 11-months out during the first and second highest DVC demand times of the year, which are the first two weeks of Dec and Christmas week (particularly time around Dec 31), but even that does not happen every year. Moreover, 1BRs are usually the last to fill and, for the time you want, those are likely to still be open even at 10 months out.
You can also book a non-owned DVC resort for up to 7-nights at exactly 8 a.m. eastern at 7-months out from date of arrival. For that availability varies, and the most difficult period is during the high to extremely high DVC demand time of the year, which at WDW is late Sep to marathon weekend in Jan, e.g., for the time you want the Epcot and MK DVC resorts can be difficult to get at 7-months out even for 1BRs.
