No it doesn't mean there is a Now router there already.
It means records show it is suitable for self-install. i.e. it is believed to have a working BT/Openreach line.
The router should be sent to arrive a couple of days before the activation date, and you just connect it yourself.
Ordering the broadband before you move in can sometimes cause problems, such as the router "going missing". Hopefully all will go well for you.
