[I see my hands]

The day before the day you die would be your longest day.. Right? :) That is unless you die no earlier than like .000000001 seconds before midnight.

But a pretty cool take on the matter!

Good news for Superman, too. He won't have to fly as fast around the Earth when he turns back time.

[presidio9]

No, the day before you die. Theoretically, I guess you could die around 12:59.9999999999999 PM. Then it would be the actual day you die. And, no, Superman will not be flying around the Earth to turn back time. It is forbidden for him to interfere with the history of mankind.