ESEA matches don't have a set time to start, although as ma3laa said most matches start between 9-12 EST. The way ESEA scheduling works is that roughly 1 week before the default match times (1030 est tuesdays and thursdays as scrimshaw said) your scheduling for the match opens up. It will give you an interface in which you can make a scheduling offer for anytime on any day that week as well as allowing you to leave notes to your opponent (ie why you can't play the default time).
So for example if your team can't play your first match at the default time, you can make an offer to your opponent to play it at XX:XX instead of 10 30 and your opponent has 24 hours to respond with either an accept or a counter offer or it automatically accepts your schedule. I would provide a picture of the interface but all of my ESEA matches are over for the season, hope this helps.