Hmm - I had no idea. I came across the distinction (philosophy/sophism) in Plato's work. I had the feeling that Sophism continued to be the normal term, without its modern pejorative sound, until the advent of christianity as the dominant ideology of the roman empire- certainly, I think the idea of philosophy as the love of (divine) wisdom is a sort of curtailment of the whole project, really only favourable to Platonists, Christians, or I guess Parimedeans- so I thought it's the kind of thing that Plato (and his school) would have put about.