when was it screened?
1973
Release
Despite unanimous praise at a January 1973 test screening attended by Universal executive Ned Tanen, the studio told Lucas they wanted to re-edit his original cut of "American Graffiti".
where was the movie american graffiti filmed at Petaluma, "Mel's Drive-In" in San Francisco, Sonoma, Richmond, Novato, and the "Buchanan Field Airport" in Concord were some of the locations.
January 1973 It was released in the United States on 11 August ,1973. UNANSWERABLE
American Graffiti American Graffiti
Release Release
Despite unanimous praise at a January 1973 test screening attended by Universal executive Ned Tanen, the studio told Lucas they wanted to re-edit his original cut of "American Graffiti".  The film was released in the United States on August 11, 1973 to sleeper hit reception. 
wiki:13447376
American Graffiti [SEP] Release
Despite unanimous praise at a January 1973 test screening attended by Universal executive Ned Tanen, the studio told Lucas they wanted to re-edit his original cut of "American Graffiti". Producer Coppola sided with Lucas against Tanen and Universal, offering to "buy the film" from the studio and reimburse it for the $775,000 (equivalent to $ million in ) it had cost to make it. 20th Century Fox and Paramount Pictures made similar offers to the studio. Universal refused these offers and told Lucas they planned to have William Hornbeck re-edit the film. When Coppola's "The Godfather" won the Academy Award for Best Picture in March 1973, Universal relented and agreed to cut only three scenes (about four minutes) from Lucas' cut—an encounter between Toad and a fast-talking car salesman, an argument between Steve and his former teacher Mr.