Called Ford Performance in reference to my "R" order today and for the second time was told that winter production is not probable due to the nature of the Michelin PSS2 tires which should not be subjected to ambient temperatures of less than 40 degrees F as the rubber can crack. He also said that "R" production will be somewhat sporadic, Ford will not build a large block of "R"'s at once, they will be intermingled between standard GT350 and regular Mustang production as they are all built on the same line. I imagine that the sourcing of things such as the hand built engines and carbon wheels cause delay.
My order status has progressed from "entered" on 10/15/2015 to "locked" 12/29/2015 with a partial VIN, according to my dealer.