Go for it. If you have an idea, jump in and do it. I started my first chapter
last week, and I still have a few pages left.
I know the conventional wisdom is to start out with an outline (synopsis),
but I'm leaving that for last. If I recall, from an answer I got from Debi,
she mentioned the word "Summary." I'm sure she'll clear it up, once she reads the thread.
I plan to do a short summary of each chapter, unless she, or someone in the know, indicates something different.