Firstly, you must know that the time your body releases an egg is generally on day 14 of your cycle.
But there are cases that some women’s body releases an egg on the 12th day, others on the 22nd.
The best estimate for ovulation occuring would be any day between 11th-21th day following the last day of your period.
Miscalculating the ovulation period is a common mistake most women do when they are TTC (Trying To Conceive).
But of course, do take note that there are cases of irregular periods, no eggs being produced during that period cycle, .etc.
The guide to chart ovulation cycle correctly is to get a Basal Body Thermometer or a ovulation prediction kit.
This will help you chart way much easier.
It would be recommended to use a digital fertility charting monitor like Clearblue Easy Fertility Monitor.
Many TTC women have conceived successfully with a Fertility Monitor since it accurately predicts their ovulation periods.