Ovulation on ultrasound..

I have just recently went to my first appointment at the fertility doctor and I had an ultrasound done. She said both my ovaries looked good and normal and that it looked like I had just recently ovulated from my left ovarie..but I forgot to ask how recent would I had ovulated because I was on day 3 of my period so how could I had ovulated? It is Saturday and I plan to call Monday when they open and ask my doctor but I'm just really curious.. Does anyone know how long ovulation show up on an ultrasound??