After the purchase, it is important that you re-center the wheels!
After some use (typically 50-100 km mileage), wheels have to be re-centered to tighten loosened spokes and nipples. This relaxation is a mechanical process that you, as a user, have to counteract for your own safety and comfort. This also contributes to the longevity of the impeller.
You can do this the quickest in your bicycle shop around the corner, as this has the know-how and the special tools.