The real achievement of Woody Allen was that he was making movies that felt very personal, and for a whole group of people, it spoke to them. Then he became an archetype, like Groucho Marx or Chaplin.
Music is like color or acting or whatever. It's really something I think about from the beginning. Not that I always know exactly what I'm going to use, but I don't see it as something like, "Let's find some songs now!" after we have a finished film.