I've recently been asked how do I know when I'm ready to start writing a book.
Before I dive in to start Chapter 1 of a book, I do a LOT of brainstorming, fine-tuning my plot, expanding on some ideas, and doing some general "what if?" brainstorming. I have a massive (almost 300 pages now) notes file that I've been piling scenes, dialogue, ideas into for years.
In my story arc, I know the beginning, the end, and a few "big moments" in the middle. But, at least for me, that's not enough to get a book started. What I'm do is turn some of the scenes and dialogue chunks in my notes into what connects those big elements: the subplots, machinations, manipulations, but most importantly, the thread that runs through the story from beginning to end, the vital element that everything else connects to and branches out from.
And as I've said before, I open a fresh Word document, go through the massive notes file and COPY and paste things I'll probably use in the book into the new Word doc. Always COPY and paste, NEVER CUT and paste. That way all of your valuable notes that you've lovingly gathered over the years remain intact.
As to how long I've had some of these notes, I'd say that some are probably at least ten years old. Never throw a dialogue snippet away; you never know when you'll use it -- or when the snippet will spawn a completely new idea.
As to how detailed of an outline I like to have before I start writing -- I need the beginning, the end, and as many of the middle elements in the plot arc as possible. That way, I have a pretty clear roadmap of where I'm going and how I'm going to get there. That said, I've learned to be open to change. While I'm writing, the story will grow and change (this happens through every draft, not just the first one). I'm learning to trust my instincts and just go along for the ride.
And how do I know when I'm ready to start the book? When I find myself opening a new Word document and typing "Chapter 1." ; )
UPCOMING EVENT: I'll be doing an online interview, live chat, and contest over on Bitten by Books next Tuesday, June 2. My publisher is offering five copies of The Trouble with Demons to the contest winners, and I'll be signing & personalizing them and including signed bookmarks. Pop over to Bitten by Books for all the details.