I've been hanging out in our dusty, empty chat room lately and could chat a bit during my lunch break if anyone stops by. I usually do lunch at about 7pm GMT / 12pm PDT.
Most of our users tend to be more active during the week, but I honestly prefer weekends. Evening hours work as well, with evenings for me occurring roughly at GMT -7, but weekday nights might be kinda tough for people in other parts of the world.
I was thinking that varying the times a bit could help get everyone involved.
UPDATE: Here is the transcript from the first chat:
http://chat.stackexchange.com/transcript/message/4876019#4876019