Historical clue formulations

• Seven-night holiday — 2023-12-28
• Subject of the 2008 documentary "The Black Candle" — 2023-07-12
• Annual holiday first celebrated in 1966 — 2019-02-01
• Year-end tradition since 1966 — 2016-07-23
• Annual celebration with candles — 2010-05-07
• December celebration — 2009-11-03