renting out what was primary residence....1031?

[Dave Currence]

The scenario is this....Purchased a condo in Manhattan in 2006, it served as our primary residence until October 2014.

Since October 2014, we have been renting it out. 

Basic question is...at what point, if any, would this property become "eligible" for a 1031 exchange.  There should be some substantial gains on the unit, both from appreciation and improvements so if there are ways to defer CGT if we should sell, that would be great.

I'd love to hear from any specialists here on BP.

Thanks!!!