Though I can work with nearly any day, I would like for the timeframe to be earlier than the evening of EST - preferably starting around 4 PM. Doing this on a weekend would allow West Coast americans to easily participate (approx. 12-1PM for California), as well as many people in Europe (it would be about 9 PM in Britain) would have a chance to take part in the JPs.
Personally as well, my work ends at 2 but it starts at 6 AM (and I work every day of the week with irregular, unpredictable exceptions), so having a JP start at, say, 8PM for me makes it difficult to participate.