When I lived just north of New Orleans I don’t remember waiting for the Government to tell us to leave. We knew the dangers in our area, kept up on what was going on and left when we saw it was needed. If we had waited for "them" we would probably still be waiting. You have to take care of yourself and your family because "they" will not. After the fact there will be help available but only to those who survived what ever catastrophe hit you.
The most important thing is to know your area and what dangers are there.