I called
DVC MS promptly at opening this morning and was somewhat surprised when I was able to book this tour for mid-October. It probably helped that I was booking exactly 180 days before a Thursday arrival for a tour on the following Wednesday. (Similar to the fact that you have a better chance of getting a FP for FoP or Slinky if your FP booking window opens up a number of days before you plan to visit AK or DHS.)
Based on some of the posts above, my expectations won't be soaring (sorry), but hey, it's FREE. How often do you get to that about something at Disney?