I am hesitant to do it too. 8 is when all the good shows come on.... Maybe I'll just go and turn off half the lights in the house... I know it sounds bad, but we do our part to try and cut electricity use. Tvs go off when we aren't in the room, I have energy efficent bulbs, recently got blackout curtains to keep the house cooler. Little things help a lot.
The point of Earth Hour is to cut energy use in a time when energy consumption is generally high. So doing it during daylight wouldn't really be helpful because no one would have their lights on anyway.
I'm going to do it, because lets face it, one hour to make a statement about energy conservation is not hard. I think getting together to talk with no computer or tv will be super fun!