Question regarding capital tax gain

Hi, Everybody,

We lived in a house for over 10 years, in May 2015, we closed a new house and moved there in July 2015.  

It has since rented. I am now planning to sell it for capital gain tax benefit. 

So my question is: Do I have to sell it by end of May this year or end of July Or anytime this year?

 

Thanks,