Need help starting my book can anybody help?

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), o have it start with one of my main character's childhood memories, dreams o nightmares. o 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, o hold off on the giving away the fact that it's a story until the story is done? o should I just jump into her daily life right of the bat? I'm sorry I can't give tu a descripción of my book but tu know how it is.