OPK help, please!

Lauren
Hi ladies - 
So as some may know, this is my first month using OPKs... And I have been waiting to see my surge. 
I've had the suspicion I ovulate later than predicted. 
Below is a picture of my strips from the past 8 days. The final one (taken 30 minutes ago) is the darkest one I've gotten... Is this my positive? Or hope that it gets darker within the next day? I don't want to confuse myself by continuing to test...
(And yes, I store them in a ziplock baggie haha)