Unless your Role or the Team you belong to has different working hours we by default start our day at 9am EST and work until 5pm EST to maximize our communication. The more hours that we have overlapping with our peers the greater our collective efforts. All conversations happen over HipChat in open rooms and video conferences via Google Hangouts and Zoom.
We do not care where you are in the world but we do care about the quality of our communication. It is very important that you have a reliable Internet connection that can consistently support video conferencing and a quiet, non-interrupt, environment from which to work.