Looking to buy a cert preowned 2015 or 2016 Toyota Rav4 LE. We have 1 car already. Should I buy now or wait til Sept?

I'm looking for a Rav4 LE AWD certified preowned 2015 or 2016. Just recently moved to Ohio. I was told that the 2018s will be coming out in October. Even though I'm going to be buying used, do you think I should wait until September to get a better deal? Also I'm paying for the entire car in full. It's not a huge deal that I have the car now since we have one car in the household. Thanks!