" In your first ten pages you can have three sentences of backstory, used all at once or spread out. In your second ten pages you can have three paragraphs of backstory, used all at once or spread out. But if you put backstory or exposition into dialogue, then you're free to use your own discretion. Just be sure the dialogue is truly what the characters would say and doesn't come off as a none-too-clever info dump. "

― James Scott Bell , Just Write: Creating Unforgettable Fiction and a Rewarding Writing Life