I wrote the text from which I taught my tech operations class and it included a brief section on theatre history. During my research I didn't find a date given for the date the first person was called a stage manager though I think good arguments could be made for the theoretical creation of the position. Was it the guy who pointed the Greek chorus toward the stage? Maybe it was the guild member who made sure the FX were set up for Medieval church playlets. We know that the prompter whistled to cue drop changes during the Italian Renaissance and the Restoration - we still don't whistle in theaters thanks to that - but does that constitute the beginning of stage management? I wonder if you're being asked for a historical quote or to think about what you know and to give an opinion along with your reasoning.