A timeline of events related to the history of Akzidenz-Grotesk (to be updated as we discover new things):
1893: Berthold expands business into type founding
1895: Schattierte Grotesk Bauer & Co is shown in specimen book
1896: Bücher-Grotesk shown/released by Berthold (later AG condensed)
November 1897: Berthold acquires Bauer & Co
1898: release of first styles under name Accidenz-Grotesk
28 April 1898: registration of 13 sizes of Accidenz-Grotesk (regular) at the German Musterregister and published in Deutscher Reichsanzeiger
September 1898: joint ad by Bauer & Berthold mentioning 13 sizes of AG (regular) in Schweitzer Graphische Nachrichten
1899: joint AG ad by Bauer & Berthold showing 13 sizes in Deutsche Buch- und Steindrucker
1900: Berthold (& Bauer) Probe showing AG and Schattierte Grotesk
late 1902: release of Royal-Grotesk
January 1903: release note about Royal-Grotesk in Archiv für Buchgewerbe
1908: Berthold acquires Theinhardt foundry (and add their offerings to the Theinhardt specimen book of 1908/09)
1911 (at the latest): Berthold type specimen catalogue published including fonts of Royal-Grotesk, Accidenz-Grotesk, Halbfette Accidenz-Grotesk, Fette Accidenz-Grotesk, Breite Akzidenz-Grotesk, Accidenz-Grotesk Skelett, Breite magere Accidenz-Grotesk, Schattierte Grotesk, Royal-Grotesk Russisch, Accidenz-Grotesk Russich, and Schattierte Grotesk Russich.