Even the Wikipedia article for Kotex concurs on this -'modern, commercial, disposable pads seem to have started in the late nineteenth century with the Hartmann company in Germany and Johnson & Johnson in the United States'.
Unmentioned there is the Southall Company in the UK, which was advertising in Family Doctor and Home Medical Adviser, c. 1893:
The greatest invention of the century for Woman's Comfort, at the cost of washing only.*
May be obtained from Ladies' Outfitters, Drapers and Chemists throughout the world
A Free Parcel of SOUTHALL'S "SANITARY TOWELS" will be sent Carriage Paid to the first Lady Stall Holder of every Bazaar who applies to THE LADY MANAGER... mentioning this paper, and enclosing circular with list of stall-holders.
FREE SAMPLES could also be sent for.
The primacy of Southalls features in the main Wikipedia article on the history of sanpro and there is yet further information, including scans of ads, on the Museum of Menstruation website
*Possibly not disposables, then.