way back when: [short for ‘way back’ followed by a clause introduced by ‘when’ indicating to a time long past] (a) used as a title for an anecdote or narrative of times past (now rare); (b) a long time ago.
1921 Hosp. Managem. Feb. 51/2 A popular feature of a metropolitan newspaper is a ‘Way Back When’ column which appears daily under the stereotyped heading ‘Do You Remember Way Back When’ and the readers contribute some reminder or other of the good old days.
1923 Rotarian June 336/1 Occasionally I have contributed..a ‘Way Back When’ recollection to the ‘Wake of the News’.
1931 S. Thompson (title) Way back when; recollections of an octogenarian.
1951 Jrnl. Amer. Water Wks Assoc. 43 1 ‘Medication’, or even worse ‘mass medication’, has been plaguing fluoridationists almost ever since it was introduced innocently enough way back when.
1984 Sounds 1 Dec. 58/6 Relative newcomers aren't always in the best position to explain what happened way back when.
1994 L. Erdrich Bingo Palace ix. 105 Zelda lives in the original log house from way back when, a place..added to over years gone by with layer on layer of Sheetrock and plaster.
1998 T. Clancy Rainbow Six xx. 381 The Worldpark job was as good a bit of sorting out as I have ever seen, even better than the Iranian Embassy job in London, way back when.