Model rooms won't be open until after sales have been announced, which might be early to mid 2017, but that is just a guess on my part and not based on anything official. I'll add your dates to our Lodgers' Log
They are only converting the South Wing. The North Wing rooms aren't undergoing any construction, other than on the 7th floor, where the OFC lounge is being moved to the North Wing's two Honeymoon Suites.
There is much more information and photos throughout the
WL DVC Expansion thread located
HERE.