I’m new to OPKs. If glow predicts that I ovulate in 2 days, but my test lines aren’t getting any darker, does that mean I probably won’t in 2 days? Are you supposed to see a slow progression of darkness or can it go from light to positive?

I am just wondering because I have to go out of town and was hoping to before I leave. My cycle is pretty regular and glow has accurately predicted my period days.