Why were the lunation counts started in 1922?

Lunation 1 on January 16, 1923 was the first lunar synodic month for which Prof. Ernest Brown at Yale University had detailed lunar occultation data for developing his mathematical models of lunar motion. The 'Brown Theory' of lunar motion forms the basis for modern predictions of lunar motion, eclipses and occultation events. A synodic month, or lunation, begins at the New Moon and runs until the next New Moon 29.5 days later.