We have played quite a bit of 4e and we have both used Roll20 quite a bit. We were previously in a campaign that took place Sunday nights at 6pm EST but we have decided we want to find something new. We're both looking to play strikers and while we have a good idea of what we want to play I don't think either of us are dead set on our current characters.
Ideally it would be with someone who is not new to DM'ing 4e and knows the rules and how they apply. It's not a problem if the campaign is already under way or if it is just starting. Sunday is ideal and Saturday should be alright as well but sometimes he works on Saturday so he might miss a session here or there.