April 9, 1977. At the Los Angeles Science Fiction, Horror and Fantasy Convention, held at the LAX Marriott from April 8-10, the Vice President of Star Wars Corporation, Charles Lippincott, presented a panel on the soon-to-be released feature film, Star Wars. Luckily for us, Barney Evans recorded that panel and uploaded the audio to YouTube on October 9, 2015. The panelists included Mark Hamill and John Dykstra. The program began with a trailer. Have a listen:

Photos of Mark Hamill signing autographs can be seen here as well as on the video.