Is SCI Impact Factor valid for a year? And, my PhD publication dilemma regarding it
Some theoretical background regarding the impact factor:

The impact factor released in the summer of year X ist the impact factor X-1 which means, it takes into account all references of the papers published in year X-1 citing papers published in the years X-2 and X-3. 

Currently, in spring 2017, the latest impact factor was released in summer 2016 and it's the impact factor 2015. It has analyzed all references of the papers published in year 2015 citing papers published in the years 2014 and 2013. 

To make a long story short, the current impact factor of a journal says nothing about the current journal and especially nothing about one single article recently published in this journal.