The easiest way to do that is to make sure that before you start the backward movement, that you actually tip the bike til you feel both feet on the ground. (At least that's what was demonstrated to me the two times I've been shown how to do it. ) It actually makes the next step easier.
That's one of my first steps, then strrrrreeeeeeetch Dita out and onto the centerstand. ( of course for most humans, unlike me, it's not a 2 minute ordeal.
)