Ovulation Timing


How does a womens body know when to O? I know it’s generally the same amount of time from month to month. However, I wonder if the size of follicles plays a roll? Does your body know when follicles are big enough and then O begins?

I’m asking this because I’m on a different dosage and comination of meds this month and I’m wondering if they will cause me to O sooner. I took 150 Clomid cd3-7 and in addition to 58 iu Follistim on CD 3-5. Has anyone heard of this?