Progesterone pessaries

My doctor has given me progesterone to help me conceive. I’ve been told to take 3 days after ovulation or my first LH surge. Now it’s Sunday and I can’t ask but unsure what to do. I got a positive one evening and then the following day. Do I count from the evening or following day? Chart posted too. I feel like day 19 would have ensured I had ovulated before I take it but she did say first positive. Worried I will take it too early or too late!