I'm calling O.S.I.'s album Office of Strategic Influence the definitive beginning of HEAVY SHOEGAZE music, elements were present already in bands
like Bob Dylan, Jimi Hendrix,
Alan Parsons Project, Radiohead, Moody Blues, Tool, Chroma Key, Pink Floyd, Deftones, Smashing Pumpkins, King Crimson, the Fates Warning's album Disconnected, Grateful Dead songs
like Touch of Grey, with the earliest beginning I suggest as early as the Miles
Davis album Kind of
Blue though SHOEGAZE is more of a hybrid of mellow blues jazz and mellow rock combined with more modern digitization, possibly successfully started with Radiohead's OK Computer album given music contributions in electronics by artists
like Aphex Twin, but also with origins as far back as Miles
Davis, but the reason OK Computer in 1997 isn't the definitive beginning is that in 2,000CE O.S.I. combined this style with the laid-back heavy edge of Tool, and Porcupine
Tree that made it HEAVY SHOEGAZE. Shoegaze refers to how it's musicians are often gazing at the stomp boxes while playing the music.