1914: The earliest occurrence of the exact phrase advent wreath in the Hathi Trust Digital Library as of 30 Dec 2024: Margarethe Müller (1862- ), Elsbeth: a story of German home life (New York: E.P. Dutton & Company, 1914), 214. Naturally, others follow. Here there are clearly more than four candles, but in this report on p. 276 of vol. 23 (no. 1 (March 4 1921)) of The Quaker: a fortnightly journal devoted to the Religious Society of Friends there are only three. Etc.
1918: The earliest recoverable hit on Adventkranz (specifically) in the Hathi Trust Digital Library as of 30 December 2024: Ernst Mummenhoff, "Das Findel- und Weisenhaus zu Nürnberg, -orts, kultur-, und wirtschaftsgeschichtlich II," on p. 102 of Mitteilungen des Vereins für Geschichte der Stadt Nürnberg Heft 22 (1918). "recoverable," I say, because OCR doesn't always work well on Fraktur. A Findelhaus is a foundling hospital or orphanage. There are no hits on the French equivalent couronne de l'Avent before 1943, and that one is in The Duden pictorial encyclopedia in five languages, in which the Advent wreath (or "garland") may bear (or at least has the circumference for) more than four candles.
