It can become available at 13 months out, but if the DC has to follow the same booking rules as the original depositing owner, then that inventory would not be accessible until 12 months out regardless of the DC reservation rules.
With MVC it is different because (multiple) weeks owners could always book at 13 months out and the DC can probably take advantage of that.
Vistana weeks have the following definitions in their Bylaws and, now that it was brought up by dioxide45, it makes more sense to me that nothing will show up until 12 months out.
Home Resort Reservation Period means the four (4)-month period beginning twelve (12) months and ending eight (8) months prior to the Check-in Day of the Vacation Period. The Home Resort Reservation Period is comprised of the Home Resort Fixed Priority Period (12-10 months) and the Home Resort Float Period.
Home Resort Fixed Priority Period means the two (2)-month period beginning twelve (12) months and ending ten (10) months prior to the Check-in Day of the Vacation Period, during which each Network Member owning a Fixed VOI has the exclusive right to reserve the Network Member's Fixed Vacation Period without competition from other Network Members, while each Network Member owning a Floating VOI competes exclusively with other Owners of VOIs at the Network Member's Home Resort to reserve Floating Vacation Periods within such Member’s Season and Unit type at the Member’s Home Resort, each subject to any limitations in the Resort Documents and the Network Rules. Not all Network Resorts will have a Home Resort Fixed Priority Period.
Home Resort Float Period means the period during which all Network Members owning VOIs at a particular Home Resort have the exclusive right to compete to reserve the use of Vacation Periods within their Season and Unit type at their Home Resort, subject to the Resort Documents and the Network Rules.