It doesn't matter whether a film is seen by a "wider audience" or not. The world premiere occurs when a work receives a public screening. Needless to say, the term can't be contorted to include the so-called completion date, which in some cases is long after the premiere. (Sokurov just edited The Second Circle, so should we reconsider the year it should be recognized by? No, of course not.) While I certainly give more weight to the WP, it's not all black and white: many communist-era films didn't receive a screening for decades.