It will certainly favour those who are awake/active when it's released. Hirk and I have very different schedules, but are presently in the same time zone. If it were released at 9 AM in our time zone, I would have a pretty big advantage. If at 9 pm, he would have the advantage. *Shrug* So it's more than just time zones. Unless you're assuming that everyone wakes up at the same number time (in their own time zone, of course) and is active at the same hours (in their own time zone, of course).
Or he could random.org a number from 0-23 and release it at that time (his time zone) on a given day.
But yeah, whoever gets to it first has a pretty strong advantage.
But it would still interest everyone to find the answer, so they could learn what the secret ability is, though. So the winner of the secret ability probably won't be published.