How Does Glow Calculate O?

J
When this cycle began, Glow said I wouldn't ovulate until next month (I normally have longer-than-average cycles.) I ovulated early, on Sunday, CD 15 which is a first, but the Glow estimate hasn't changed. I even added positive OPKs, bbt, and CM. I got my crosshairs on fertility friend this morning, and I'm 3 DPO.