Ttc I heard the best time to have intercourse is three days before ovulation how probable is pregnancy around that time frame thank you for your time?

Pregnancy. The best estimate that I have seen is a 28% chance of getting pregnant with intercourse 3 days before ovulation. Intercourse on day of ovulation has a lower chance of around 5%. Note that this is a remarkably challenging question to study, and any individual's odds will be unpredictable and different. Best wishes.