What is best day to have sonogram of ovaries to determine what is ovulatory and what shouldnt be there?

Usually midcycle. Ovulation is about 14 days before menses but varies. Have doc get cycle history and choose a day before predicted ovulation then other scans as needed for timing. Can use opk and call doc for scan to confirm. If meds, then scan after a few days of treatment. Review with doc. Best wishes.
Depends on. There's not 1 best day, it depends what you're trying to learn. If ttc what plan you are on: natural or stimulated cycle (they're different?) if monitoring leading up to ovulation then 1-2 days before anticipated works, if monitoring to confirm ovulation then 3 days afterward is better. Best time to check for 'abnormal' cysts is usually cd 3-5. Stimulated cycles need to be monitored more often.