Follicle sizes

El

On Thursday had my baseline scan on CD12 and I only have 1 follicle measuring 16mm on my right side. The nurse told us the days to have sex which we have been but my question is what is the ideal size of a follicle for ovulation and is 1 follicle enough. I don't know the thickness of my lining because my uterus was too foggy on screen and at an awkward angle.