I was called Jan 1st at 0845, for the phone interview, then mid February to schedule the phase 3 interview (face to face). I interviewed on St. Pattys day (see aviationinterviews.com), then did the Phase 4 interview a week later (HR type questions-mostly-- why us, what do you expect us to do for you, what are you flying currently, what type of engine did the P-3 have -not really HR- but they asked it; is it ok if upgrade time is long (4+years)). Start researching the company, I'm talking stock price, company officers, order a copy of "From worst to first" by Gordon Bethune, ask lots of questions on this forum if you feel like it. Do all your normal prep for an interview regarding professional knowledge. The ATP oral PTS seemed like it had a bunch of questions they were asking. Get your logbooks in order, and come up with some answers to both the situation and HR questions that you see posted on aviationinterviews.com (under ExpressJet). Best of luck, PM if'n you want to talk umm hmmm (sling blade voice).
--Matt