Not ovulating? Taking it wrong?

I just started these opk tests and I started on CD12 since that’s when Glow said my ovulation time would start with a peak on CD 15. But it’s disappeared? Should I be starting these shortly after my period? I take them at the same time every night. My period is regular at 30 days nearly exactly for the last 4 months so I didn’t worry about ovulation. We just came off a break and I figured why not use these up I bought for the cheap pregnancy tests lol didn’t wanna waste the ovulation tests too