How accurate is Glow??

Kay • TTC baby #1 ❤️

How accurate is Glow on your ovulation day. I just recently got some OPK’s. Glow said my ovulation day is the 11th. The past 3-4 days my opks has a faint line and got darker and darker but today there was barely a line at all. Wondering if I already ovulated and glow is off??