Using the numbers here I've compiled kill totals and graphed some of them in various ways. It seems it's safest to be around Jack around early afternoon-early evening, then it's wise to stay away as he starts his killing spree.
That graph is pretty cool using the BC information I always like things with numbers. I saw you updated I have to say great work! When season 6 is over I hope you updated it as well. I've been tossing around the idea of starting a non spoiler 24 blog I'll make sure to post about findings!
It does reveal some interesting things at a glance. I've had people say "what the hell happened in Episode 6 of Season 4?". There seem to be some trends too, like a quiet period before the season finale where he usually has 1-2 kills.
The season six trend I think will prove interesting. With a slow start of only two kills in five episodes it could be awhile before we see another one. Are we going to see an upward trend towards the end? I think we are hopefully in a big way ;-)