I think Hotlinks can reassure you: you don't have to wait at all, you can just have sex if you want and then you will see if there is a pregnancy or not.
That story of those three days comes from men who have reduced fertility. Then it is sometimes recommended not to ejaculate every day, but to wait a few days and then have sex when the chance of conception is greatest. And that chance is greatest around twelve to fourteen days after the first day of the woman's menstrual period, when she will ovulate or ovulate.
If you would like to become pregnant, you can keep that in mind and when you have sex around those days (may be every day if you want), the chance of getting pregnant is high. Incidentally, Hotlinks must add that it almost always takes a number of menstrual cycles before the woman becomes pregnant. So if it doesn't work out for the first few months, don't panic, that's normal! Only if it doesn't work for a whole year you can go to the doctor and discuss what to do. Have fun.