Confirmed this with Dva. The easiest way to see it is to click a spot to move her to, then before she gets there press Shift+1 (assuming you have Medallion on hotkey 1). She will activate it without the CD starting. I found this in both Try Mode and an AI game.
It only works in mech mode, not pilot mode. If you allow her to reach her programmed destination she will again activate it but this time with the CD going on. You can instead manually move her before reaching the destination to avoid having it go on CD. In fact, if you click on the map to move her to a really far spot you can repeatedly spam Shift+1 to get unstoppable all the way there.
I found if I tried this with Fenix, for instance, he would not activate along the way, but would activate (with CD) when reaching the destination.