From what I was told, having a csection should not effect when your milk comes in. I had a friend who had her baby at 25 weeks and the nurse explained to her that hormones are released when your placenta is delivered to stimulate your body to know to produce milk, regardless of how it is delivered.
That being said, it may be difficult to get to nurse right away so be prepared for that. I told my friend to be my advocate for nursing as soon as possible after my last csection. She was really on top of it too, unfortunatly my little guy had some trouble breathing due to mucus in his lungs. The nurse finally told her he had to be able to breathe before he could nurse, I told her good job, but you can back off. Once he was out of trouble they brought him in and we got started.