Todays dilemma.

[A Place of Light]

Congratulations, you've just invented the time machine.
The only problem is it's only good for one return (or one way depending what you have in mind) trip. Let's say for the sake of argument it polarizes something in the atmosphere so you couldn't just build a new one and so on and so on.

So, knowing you can only make one trip, be it to "undo" something in the past or see something that happened before you were born, where (or rather when) would you go?