So you are undergoing follicular scans and the doctor is given you Hcg injections, now when is the best time to have relations? Generally the Hcg helps the ovulation, after 24 to 36 hours after it has been given. So after one to one and half days is the best time to have relations after the Hcg has been given and you can have atleast twice in a day and the next day as well. So the chances of the sperm in abundance will be there and the chances of pregnancy will increase. So after that you also have to get another scan done just to confirm that ovulation has happened and then some progesterone can be started for you.