First off, really lovely work for your first sock on DPNS!! :cheering:
What I would do, since your first row of your heel flap is a knit row, is slip that one stitch that has the working yarn on it onto the needle immediately next to it. Then I would just slip stitches between the other needles until you arrive at your 32 on the one and 16 on the others, keeping the one with the working yarn as the first stitch on the needle with the RS facing.
Does that help??
(Don't be afraid to just keep moving the stitches around by slipping them as if to knit from one needle to the next until you get the right numbers, you will not screw anything up by slipping stitches around.)