Is 10/16/2011 the right date to consider as the starting day of their 5 year continues residency and when can they apply for citizenship?

I am sending this email to determine when I can start the process of my parents' US citizenship application. The following is the time table of my parents' travels abroad, since they got their green card. My mother got her green card in July 2007 and my father got his in January 2008. Since 10/16/2011, they have come to the US and gone out. Based on that way, they can keep their continued residency. They have not been out of the US for more than 6 months and they have been in the US around 32 months since then (more than 30 month requirement). However, between 10/30/2011 and 12/9/2012, they have made three trips abroad, every time they have been out for around 4 months and in the US for around 2 weeks. In the other words, during that period of time they have just lived in the US around 1.5 months.