Nuvaring

Can someone simplify when to insert and remove Nuvaring? I just got it today and my period should start tomorrow or sometime this week (I'm irregular). Does the day you put it in count as day 1 or the day after? Like put it in on November 29th and remove December 19th..new one on December 25th? Maybe I'm over complicating this but I want to make sure I'm doing it right.