You really need to look at least once a day, or you might miss out. THe reason being that these things sells out (max coop qty) in under 24 hours.
To request notifications from a specific board, click the "notify" button in the index of that board.
Go to the Current Coop's folder, then click on 'notify' button in the upper right corner (green) ... it should email you when a new topic is posted under 'current coops'. You just have to check your email or this board often ... at least once or twice a day.