OPK Clearblue help! PLEASE!

Hello all! This is my first month TTC. I took the advanced Clearblue ovulation test on January 17th and 18th and got the flashing smiley, meaning my fertility was "high." I then took it again on January 19th and got my solid smiley aka PEAK fertility. According to Glow, I had a 33% chance of getting prego on the 19th. My hubby and I had sex on the 17th, 18th and 19th. How the heck do I know what day I ovulated? Do you ovulate when the OPK test says you're at your peak or shortly after? What do you think my chances are? We've been together for 6 years, this is long overdue!