I've pinpointed the origins of my cinephilia as Husbands and Wives (1991, age 15), Safe (1995, age 20), and My Life to Live (first seen by me in 1995, age 20).
But... I do recall a childhood summer (age 11? 12? 13?) when I asked a neighbor to tape some movies off HBO for me (we didn't have cable), and I watched them all summer long: The Purple Rose of Cairo, Raising Arizona, and Hope and Glory. All of which I still think of as excellent films, and remembering the myriad occasions over that summer on which I watched and re-watched this triple feature... yes, that may be the actual origin of my cinephilia. I've loved Woody Allen for as long as I can remember, though... probably even before I saw any of his films, I just thought he was the most unique, interesting, intelligent, oddly funny personality.