I have a bottle made in 1894 or 1895 with Registered on it.
Definitely seen by the mid 1890s, but I suspect it goes back to the early 1890s in some areas.
Registered probably meant the facility was inspected and licensed by a government entity to ensure product safety. Asfor it being mandated nationally, that'd be too hard to enforce. It may have been mandated in some counties or cities though.