We are arriving at Napoli Airport at 6 am. So, our plan is to take Alibus to Mollo Beverello Port. Hopefully drop our luggage off and walk to Galleria Umberto. Spend a little time there and then catch the ferry to Sorrento. Where is the luggage storage in that area?
See this thread from a year ago: https://community.ricksteves.com/travel-forum/italy/naples-luggage-storage-d27e694e-3af4-402b-8d66-58df600f1538.