Question about ovulation! Please read!

Amanda • Hey! My names Amanda. Ive been married for a littlw less than two years and am ttc. Would love to hear from ladies who are in the same boat.
If you test positive on an opk you are going to ovulate in 12-24 hours right? But they say that a surge could last as lottle as a few hours... well after that positive, if ur tests start to fade that same day does that mean you already ovulated? Or do you still ovulate in 12-24 hours after u get ur positive?