How old is Naruto throughout the show's timeline? I am curious about Naruto's aging through the series from Naruto to the beginning of Naruto Shippuden. From what I've gathered Naruto's birthday is in October. 

Under the assumption that he was 12 at the start of the series. I think it went something like the following : 


Age 13 during the Chunin Exams
Age 14 when Sasuke left the leaf
Age 16 when came back from training with Jiraya 


Can someone confirm if this is correct?
From the Naruto wiki (Part II as in Shippuden):

Age   Part I: 12-13  
      Part II: 15-17


So by the end of the manga/anime, he's 17 before the larger timeskip.

Also, there was a good answer by Mike Ante on another related question.