I am sure it has been done with less, but you should be prepared to write and throw away a million words of finished material. By finished, I mean completed, done, ready to submit, and written as well as you know how at the time you wrote it. You may be ashamed of it later, but that's another story.
Jerry PournelleThe Aztecs believe they started up in what's now New Mexico, and wandered for 10,000 years before they got down into where they are now, in Mexico City. That's a weird legend.
Jerry Pournelle