I give up. I guess the answer is "it depends."
Yes there would be an NRST on new build homes held in inventory by developers across the implementation date. The developer selling the home in that case receives a credit against NRST received from the purchaser allowing maket adjustment of pricing to equalize with homes built after the implementation that have no payroll income taxes associated in their construction.
The the total cost(including NRST) to the buyer will be the same for both situations.