This is the earliest advert for the Cyclo Witmy that I have ever seen. If I read it right, it claims that the Witmy was launched on 8th March 1933.

(Source gallica.bnf.fr/ Bibliothèque nationale de France)

• Publisher: La Roue
• Country: France
• Date: April 1933
• Derailleur brands: Cyclo
• Derailleurs: Cyclo Witmy