ExpATCO,
By law you can't be issued a formal contract until you have a work permit. You may get a draft copy in an email but that will be all. If you have filled out your application for the work permit it will take about four weeks to process once it arrives back in Ireland. The IAA will then send you your work permit together with your contract and letters to obtain bank accounts etc.
In terms of staff who are already here, the people thelowestlevel mentioned started from other courses. The people on your course will start at the same as you and the ones I am aware of wont arrive until early - mid October.