I've said it before, I'll say it again:
If someone randoms you, you get one free kill. If you kill them more times than they random you, you're also randoming.
I think that time period is a hard one: PST Sents are still asleep, and European and EST Sents are at work/school. Not sure what time it would be for the Asia/Aussie/New Zealand Sents, but I think that's the middle of the night there.
-Throbblefoot