Glow ovulation/fertile days accurate?

Angela
3rd month TTC. Glow predicted my fertile week to have started Saturday with ovulation expected around Sept 2nd. However I had signs of ovulation (pains, cramping) 3 days before fertile window was to start. Anyone else get ovulation sooner than predicted? I know they can't be exact on Glow but curious about other experiences. I have not tried opks yet, waiting til 6 months in before I do those.