I'm not official, but as you're still waiting: All SAs take place during the movement phase unless they state otherwise (although the effects of some don't happen until the end phase e.g. All Hands On Deck and Scramble). Stand Down is performed in the movement phase. I'd expect that your ship(s) have to be within the range necessary to accomplish this SA after they've moved, just like they do with Launch Breaching Pods And Shuttles.