Ovulation depends on your menstrual cycle. If you ideally have a regular cycle of 28 to 30 days, the 1st day of your cycle will begin with your menstrual period.  After the 10th day you begin ovulating, and will most likely ovulate on the 12th, 14th, 16th, and 18th day of your cycle. Methods such as checking basal body temperature, observing cervical discharge, vaginal fluid, and tracking periods helps better understand the time of ovulation.