Before seeing the dealer, try to narrow down when the
vibration occurs. When you touch the brakes? On turns? When
accelerating? Only when driving below X mph? During warmup
but not after warmup? At all times?

Try to get a friend to stand outside the car while driving
and see if they can narrow down the source.

Exhaust heat shields are one of the most common causes of
minor vibration noise on cars. (Some of us just remove
them... ) But your car should be under warranty, so if this
is serious noise, it should be repaired by the dealer.