<b>Before Napoleon there was no such thing as surnames</b> not really, it depends on the country of course but surnames more or less as we know them today go back at least 600 years in England and France, while Iceland still does not use them today, instead people are known as “X son of Y” or the like, similar to how we are called to the Torah (but obviously with a very different grammar)
As for when Jews started using surnames it rather depends on what country they were in, and probably social class and half a dozen other things.