Well, I found this on Blackadar Marine Insurance website. It pretty much sums up when the step hull was designed;
This hull design is not new. In fact, it would seem the original idea was formulated by Rev. C.M. Ramus of Sussex, England in 1872. He reported to the Commission of the Admiralty that he discovered a way to make the speed of ships double, and published Improved section drawing of a Stepped Hull later that same year. And the records also indicate that the first patent was awarded to a 20, 7-step boat named PIONEER, designed and built by William Henry Fauber in 1908. Several race boats used the stepped design in the early 1900s. Military seaplanes also incorporated this design in the 1930s and 1940s.
If you want to see the latest innovation of the stepped bottom look at only two boats: The Phantoms out of Florida and the 40 Hallett out of California
I believe the most inovative have been the Formula Fast-Tec and the Outerlimits hulls.