OPK doesn’t match with BBT Spike

Ma

I got a peak positive OPK on the 17th, our <a href="https://glowing.com/glow-fertility-program">IUI</a> was the 18th (+ egg white CM) but based on my temps I ovulated on the 20th. Did we do the <a href="https://glowing.com/glow-fertility-program">IUI</a> too early? Would you say we ovulated on the 20th?