It wasn't Bush's job to evacuate NO. He informed the people who were responsible... what did they do? (actually a streight question, did they react quickly?)
No, the evacuation order came very late compared to what was known. Katrina was a Category 3 and strengthening a full week before it hit. It was a very slow moving storm (which is why there was so much warning and also why it was so dangerous). The projected path was known a week before it hit. I don't think the evacuation order was issued by the Governor and Mayor until Saturday or Sunday.
But I don't think anyone thought the leavee would fail. I think people thought water might come over the top, but not fail completely. The New Orleans city page tells it all. It's stuck in time to before the storm. The mayor is actually telling people how to ride out the storm.