Continue to rent or sell sooner to claim 121 exclusion?

[Gwen St. Pierre]

Hi - I have a rental that I lived in from July 2012-July 2015, it has been rented since then. We are looking for new tenants to move in on 8/1/2017. My question is, if we have tenants in there until the end of 8/2018 and then we decide to sell, are we going to have to pay taxes on the proceeds? I know that the 121 exclusion says we have to have lived there 2 out of the last 5 years, if I understand that correctly then we must sell by July 2018 or we lose the exemption?

If that is the case then we will likely sell now or get the tenant to sign a 9 month lease instead of a 12 month one so we can put it on the market in April of 2018 to sell in time to avoid paying the taxes.

Thoughts? Am I understanding this correctly?