Homeworks are just advisory; stuff you should be doing but we're not going to always check if you do. But they are good for you! This is somewhat akin to eating vegetables or exercising; you can get away with not doing them, but eventually it will catch up with you (e.g., on exams, or projects, or both). So do them!
September: Read intro chapter of textbook; do all of the practice problems (and check your answers); read as much of K+R book as possible.
October: Read chapter three; do the practice problems and check your answers.