You can buy an ovulation test from any drug/convenience store. It is taken just like a pregnancy test, and it tells you when you ovulate.

You could also try to chart it yourself. Pay attention to your cervical mucus and your temperature. There are many charts out there to help you with that if you search google.

What Penguin said. You can't tell from physical symptoms exactly when it happens; cervical mucus and basal temperature can help predict ovulation, but only an ovulation pee test can tell you for sure.