I bought a new car out of state recently and it took almost 2 months to get my plates, registration and title. The title actually arrived first, since it was mailed directly to me (reg/plates are mailed to the dealership, then re-mailed to you).

Just keep an eye on the expiration date for your temporary reg/plates and if needed, the dealership should be able to get them extended (temps are usually good for 2 months). Best of luck!