I'm going back in time. Where should I go? What do I do?
Going back in time will change the Now.
Our Now will no longer be what we know it to be because what I do then will have a ripple effect that changes our present.
Knowing that I can't come back and the thread to this present will be forever severed, how far back should I go and what should I change?
Mind you that You, in all likelihood, may never be and your concerns for the present will be moot.
To when do I go?
What do I change?
This is a fantasy outside of what we know of quantum mechanics. Assume that I have a magic talisman that can translate me to the past. The debate is premised on what should and/or shouldn't be done when I travel back in time.