Not sure about the day, but you can also identify your fertility when your discharge is clear, like (uncooked) egg white clear. That kind of discharge helps the sperm to move up. We had sex the day after I saw that discharge and now I'm 3 months pregnant. And also don't forget to pray if you're religious 😊
Count 12 days from first day of mens. Have sex on the 12th day, 14th, 16th, 18th and 20th. Do it in morning. Eat a lot of healthy food and take vitamins. Kayo pareho ni husband.