During the first 12 months understand that it means that a particular service, for example, a routine dental cleaning, is covered 2 times with in a 12 month period, but what about the second 12 month period,and the third and so on. Is it always based the dates of coverage of the very first 2 cleanings in that first 12 month period, or does it change based on when the last two were covered in the previous 12 month period? For example if the very first 2 were covered on 3/16/04 & 6/23/04 and the next two were covered on 4/16/05 & 9/13/05, are the next two eligible 3/16/06 & 6/23/06 or 4/16/06 & 9/13/06?