The 65-year-old actor, who starred as Jedi Knight Luke Skywalker in the three original sci-fi films, says fans made fun of the project when "A New Hope" hit screens back in 1977, according to The Hollywood Reporter.
"At the end of the trailer it said: 'a billion light years in the making. And it's coming to your galaxy this summer.' Somebody in the balcony yelled out: 'yeah and it's coming to the Late Show two weeks after that'," he says.
Hamill recently returned to the 'Star Wars' franchise for the 2015 "The Force Awakens" and will be starring in the upcoming "The Last Jedi".