From the Walking Dead wiki
Episode 2: Starved for Help - May 30th, 2012Episode 3: Long Road Ahead - June 25th, 2012Episode 4: Around Every Corner - July 27th, 2012Episode 5: No Time Left - August 29th, 2012
You can't count on it being completely accurate or there being a delay. However it is a monthly episodic game, so May seems most likely.
Warning possible game spoilers in the link.