If we assume people are doing this in their spare time, then a weekend is the best time to do it: say noon Pacific time, which is 9pm Berlin time. But people might want to be doing something else with their Saturdays or Sundays. If they’re doing it with their weekday evenings, then they just don’t overlap; the best you can probably do is post at 10am Pacific time on (say) a Monday, and let Europe and UK comment first, then the East Coast, and finally the West Coast. Obviously there will be participants in other timezones, but those four will probably cover most participants.
That’s a tricky problem!
If we assume people are doing this in their spare time, then a weekend is the best time to do it: say noon Pacific time, which is 9pm Berlin time. But people might want to be doing something else with their Saturdays or Sundays. If they’re doing it with their weekday evenings, then they just don’t overlap; the best you can probably do is post at 10am Pacific time on (say) a Monday, and let Europe and UK comment first, then the East Coast, and finally the West Coast. Obviously there will be participants in other timezones, but those four will probably cover most participants.