Wait an extra day or two before grouting, Greg. Prolly won't need it, but it'll make you feel better.
VersaBond will cure just fine sealed in double ZipLock baggies, so I'd expect it to cure under your tiles.
Your bigger concern is just the thick build-up of thinset under the tile installation over the Ditra. Not so much the curing, but the loss of the design function of the Ditra membrane. Herr Schluter wants the tile should be stuck directly onto the membrane for best results. The type of installation you have with those small sections makes the Ditra pretty much redundant, of course, and you should
have no problems with the installation, I shouldn't think.
What sort of caulk do you plan for the perimeter of each of those tile sections?
My opinion; worth price charged.