What Does This Follicular Study Report Indicate?

I had an Ultrasound done on 11th day and the left overy dominant follicle measures 25.5*19.1mm with ET-7.9mm and no free fluid in POD ..I repeated on 12th day and the left ovary dominant follice measures 19.8*19.1mm with other readings remained same as the previous day. Suggest me when we should have an intercourse to get pregnant.Thanks,
Lakshmi