Maybe it would be best at the one month of ownership phone call I think they should do (after getting permission from the owner to make the call) in which they reinforce the battery contract that was signed, why the car should be plugged in, and the risks of not plugging the car in for extended periods. During the phone call they could talk about the Supercharging network they are building. They could say it will take years to build out but that they are asking owners what location they would like to see a charger and that they are building a database of owner requests to see where the ideal locations are to place Superchargers.
The main purpose of asking people their desired location would be to see what they thought would be a good location for a Supercharger. If enough people were clustered in a certain city that wasn't anywhere near a Tesla Store but all requested a similar town for a Supercharger, then that location would also work well for those owners.