**FEMA was given full authority to respond to Katrina on August 27, Specifically, FEMA was authorized to "identify, mobilize, and provide at its discretion, equipment and resources necessary to alleviate the impacts of the emergency." FEMA's head, Michael Brown, did not hear about the covention center until September 1, and the first food convoys didn't arrive until September 2.
** The mandatory evacuation order was issued on August 28. By that evening 30,000 people were in the Superdome with a 36-hour food and water supply. Bush left his vacation home, and finally "flew to Washington to begin work" on August 31
** Bush was warned about the possibilty of levee failure on August 28. On September 1 he said, "“I don’t think anybody anticipated the breach of the levees."
** The levee broke on the morning of August 29. Michael Chertoff, head of the DHS, says he found out about it 24 hours later.
Links to support this and more are all here