My car was delivered Feb 1st and my plates came in the mail on March 2nd. I would call the Tesla location where you picked up and ask for a copy of the REG 397 Title Application. I needed to get a copy of mine in order to submit my CVRP application. You can probably also confirm that they sent it in.
Also I'm not sure if this matters or not, but when I received my license plates, the return address on the package was Tesla headquarters...so does that mean Tesla has plate inventory and is registering and sending out plates on behalf of the DMV?