I began my first novel when I was 15. It went through three drafts, of around 40,000 words each. If I find it, I'll burn it.
Charles StrossAn important factor to note is that it's rare for anyone to sell a first novel written before they turned 30-35; long-format fiction tends to require a bunch of experience of human life that takes time to acquire. So your average mid-career novelist is in their forties to fifties!
Charles Stross