How should I start my book?

I have everything else planed out I just need help with chapter one page one. I was thinking of started it with some kind of a story that tells how everything began, (seeing how it's a biblical supernatural book), or have it start with one of my main character's childhood memories, dreams or nightmares. Or if I go with the idea of it being a story should I have the main character (seeing how when the story would be told she is a little kid) interrupt making it obvious that it is a story, or hold off on the giving away the fact that it's a story until the story is done? Or should I just jump into her daily life right of the bat? I'm sorry I can't give you a paglalarawan of my book but you know how it is.