I have tried many different ways to try to find where it is stored, but have had no luck.
The first 747-8 built was not a protype, but a production unit. The first delivered aircraft in both the versions (747-8i Intercontinenal and 747-8F Freighter) are in service, the Passenger version with Lufthansa and the cargo version with Cargolux.
The first 747-8 customer was Cargolux for the 747-8F version.
The first 747 ever built, 747 RA001 'City of Everett' is in Museum of Flight in Seattle.