Mercedes are strange to deal with, you go to the dealership and the dealer requests a car to be built to your spec, you then get an email at some point later to say they have found a car, which your dealer then needs to order. Make sure at this point to get the vin number, and get your dealer to add it to the Mercedes app for you, when they have done this it seems to be assigned to you. From this point it should be about 5 weeks or so to get to your dealer.
Mine should be at the dealer 6 march so cannot wait