The first advert, that I have, for the Terrot Modèle HT 4 speed derailleur system dates from March 1912. This advert, dating from only one month later, is the earliest that I have for the (extremely similar) Audouard 8 speed system. Note the lack of front derailleur.
I like the idea of ‘la triomphatrice incontestable’ - the Audouard system had clearly cleaned up at the Concours de ATF in August 1911.
(Source gallica.bnf.fr/ Bibliothèque nationale de France)