Why does the countdown clock say 8h and change for you guys, and it says 9h and change for me?

I get there are time zones, but why does this have a different effect on the start time of the proceedings, depending on where I live? The way I see it, some dude should start talking on the other side of the planet, and at that time all of our countdown clocks should be at zero, regardless of our orientation towards (or away) from the sun. Am I wrong?

Are we sure this countdown clock is accurate?