In MD if tags are transferred from a tradein to a new car, does the new car registration have to wait till the title on the tradein is in dealers name

I bought a new car about 2 weeks ago and traded in my old one. I had the tags transferred from the old one to the new one. The dealer gave me a temp registration and said he would apply for a new one. Yesterday (about 2 weeks later) he called me indicating that he had forgotten to ask me for the title of my trade in. I am planning to give him the title today. What I found though is that he still hasnt applied for the registration of the new car. He says he cannot do that till he transfers the title of the tradein to his name (because plates were transferred from the trade in to the new vehicle). I didnt think the 2 were related. I am going to call the MVA to confirm but figured I would check in anyone else had a similar experience. Also if he applies for the registration today, would that be enough time to get a new registration in 2 weeks (I assume the temp registration will expire after 30 days?)