Never go to Tolkien for council, for he will say both no and yes.
But my (much less scholarly) opinion is that if Elves served as the prototype for orcs, whether directly or as a "model" for a different clay, the corruption could have started as early as in Utumno. I recall that Morgoth's servants would pose as Orome and kill/kidnap stray Elves - and who is to say that he didn't kidnap them for his experiments, amongst other purposes?