Ovulation Cramps/Spotting... before or after ovulation?

Divina

My OPT was positive on Saturday, negative on Sunday. This morning (Monday) I had some light pink spotting and mild cramping. Does this signal the start of ovulation or the end? The <a href="https://play.google.com/store/apps/details?id=com.glow.android">Glow app</a> indicated I ovulated on Saturday so I just want to make sure I’m keeping track correctly?