I usually pants a first exploration draft and then outline what I've written. Then I can stand back and see what a mess I have to play with.

The next draft is a slightly more coherent exploration that starts to focus instead of splash around. I do a ton of notetaking and thinking after this draft, and update the outline.

The third draft is where the thing starts to look like a story that might hang together. The plot holes get smaller, the characters deeper and more motivated, the central focus clearer. After this draft, I outline in detail to work out where I can simplify, deepen and fill holes.

So in general, I outline *after* the drafts to see what I have, not just to plan where I'm going. If I write an outline before I write a draft of the book, I end up with hackneyed plots and characters pushed into situations that aren't natural to them because I don't know them yet. All the character spreadsheets in the world won't get me to know them. Writing does. Since my stories are deeply character-oriented, I have to write first and then find the natural structure afterward.