After you deny a villager's moving ping, you can save and quit and travel forward as far as you want, like a week or even months. No one should move out.. (maybe change the time on 3DS clock and make a new character to make sure?) Tho if you don't wanna get messy hair and have villagers call you a stranger so do it within ~10-15 days? >.< when you deny a moving ping, game requires some days (maybe at least a day) to choose another villager that wants to move or something.. so you can TT forward safely. hope it makes sense!