Wa'alaikumassalam! OPK tu untuk detect LH surge, yang usually terjadi 24-36 jam sebelum ovulation, so lepas dapat result +ve tu memang terbaik time to try. Honestly, most moms stop celup after dapat +ve sebab dah tahu window dah bukak, tapi some orang suka continue for 1-2 hari lagi just to confirm pattern dia (especially kalau mau double-check). Timing wise, lepas +ve results, the fertile window tu usually dalam 24-48 jam je, so boleh stop after itu or kalau dah hasilkan confirmed +ve, masa dah cukup lor. Best approach is ikut cycle pattern kamu sendiri, some girls surge lama sikit, some cepat je, so track selama few months pastu baru understand your own rhythm better!