It can't happen in the exact same nanosecond (the book might be writen in the same year or even day but not that close) none of those thing could (then it would start a the same exact second as the book is made, oh wait it would still happen after that point anyway as soon as any amount of time has passed) In back to the future he does travel back in time but it happens in the future (if it hadn't then he would have time traveled before the movie was made which would make it aternative history) back to the "now" thing; the present (aka when the work of fiction was made) doesn't change so it has to move past it, right
EDIT:
@Keris: Doubt the rules if you want I just said what I've been told. And Robin exists in the past so it's still in the past unless he live longenough to go past the present whereas Marty starts in the future (there goes several hours) whether or not he get's to the past is irrelevant since it technically happenbs past the present (the time travel starts in the future so it's a future event)