For a description of changes of signigficance made in the past, which is more than the three mentioned above, see my post
http://www.disboards.com/threads/dvc-point-reallocations.3443405/#post-54337848.
For a discussion and description of walking go to this thread:
http://www.disboards.com/threads/grand-villa-at-bw-how-to-improve-my-chances.3428795/#post-54042346.
As an example, from the subject of your post, "Reservations for Holidays," and your mention of going next October, that indicates you may be going around Columbus Day weekend. That weekend, the Thurs to Mon, is one of the highest DVC demand weekends of the year. If you own at any of the following and are seeking the rooms designated, you should plan to be online at 8 a.m. 11 months out from arrival date to make the reservation because if you wait to call when MS opens at 9, there is some risk these rooms may already be gone for Columbus Day weekend: (a) VGF studios, (b) BLT standard view, any size room, (c) AKV value studios and 2BRs; and (c) BWV standard and boardwallk view studios and two bedrooms. In fact, particularly for the VGF studios, BLT standard, and AKV value rooms, you should consider walking the reservation because the rooms have some risk of disappearing before 11 months out for that time period....