Question on 2 out of 5 year rule when selling a house

[Sarah Present]

We are in the process of selling a home and wondered if anyone can clarify on the detail of the 2 out of 5 year rule.  The house being sold, was last lived in on November 6, 2014 by us/the owner.  It is being marketed to sell now, so the question is, is it mandatory to be sold/close November 6, 2017?  Or is it by the end of the tax year?  What are the specifics on this to avoid capital gains tax in this situation?  Any help much appreciated!  

Sarah