O2 sensor isn't ready
 

I recently bought an g37 2013 coupe from a state that doesn't required smog and brought it to California which requires smog, my car has been saying my oxygen sensor isn't ready even though I drove around 2.5k miles then replaced the faulty sensor to have the same problem all I've been recommended is to drive but my car isn't registered I don't know how to fix this since I need to smog my car to register it any advice ?

1. Get a temp tag from the state you bought it from
2. Need someone to hook an OBD2 scanner up to see what's going on - not just codes.