As of last update in 2013 the .ie Zone reloads every odd hour. So a domain that was registered at 12 noon will then be live at 13:00. This goes the same with domains that were suspended and then renewed.
The times are as follows in the 24 hour clock:
01:00, 03:00, 05:00, 07:00, 09:00, 11,00, 13:00, 15:00, 17:00, 19:00, 21:00, 23:00