Yup usually before and leading up to ovulation. If you want more accuracy add bbt to confirm ovulation Opks don’t confirm ovulation or dpo. Add bbt and you will know when you ovulated, dpo, luteal phase length (is from the day after ovulation to period which stays the same each cycle give or take 1-2 days. Average length is 12-14 days give or take 1-2 days.) when period is coming by temp drop or if you miss your period and your temp stays up then there is a chance for pregnancy