Talk to everyone in your village until someone either mentions who the mover is or start talking about "rumors." If you hear dialog mentioning rumors from atleast 2 villagers in your town that means no one is moving at the moment and you are safe to TT.
If you find out who is moving from a different villager but you aren't getting a ping talk to the mover then go diving or on your beach for 5 minutes(or somewhere outside and out of site from any villagers) and after go back up and walk in front of the mover. More than likely they will ping you and if not just repeat till they do!
Hopefully I helped, I'm awful at explaining ^^