I really don't see a need for a long pre-opening sales period. DVD could commence sales six months before the opening, or perhaps even less.
Agree. It really just depends upon when Disney wants to start booking revenue from the new sales. Buyers will be ready to purchase points in March, April, May...or whenever sales commence.
Sales for Animal Kingdom Villas could also be playing a role. As of mid-February, they appeared to be down to the last 800K points in AKV. Over the last 12 months, AKV sales have averaged about 100K points per month. And the recent webcasts may have bumped that number up a bit.
Even with Grand Floridian being publicly announced,
DVC may want to get AKV as close to sell-out as possible before introducing VGF. In the grand scheme of things, I'm not sure how DVC is harmed if they wait until May, June, July or beyond to begin sales. The only thing which makes this unique is the shorter pre-opening period than other recent resorts.
As for construction being behind schedule, it's always possible. They have 9 months until the end of the year. I've looked at photos of BLT from 9 months before opening but it's difficult to draw any direct comparisons since the construction materials are so much different. The concrete and glass exterior of BLT was largely complete but the interior was little more than aluminum studs.
VGF is a more traditional structure but the rooms were pre-fabricated. A lot of the interior finishing work is already done.
I don't see any reason why they could not have the VGF exterior siding, roofing and landscape done in less than 9 months' time. But it's impossible to know exactly where things stand with regard to the interiors.