I agree with the previous user. Also you could start by using ovulation tests and when you notice the line starting to get darker have sex every other day. My doctor gave me some good advice. He said count 8-9 days after your period starts and have sex every other day from that day.
Try having sex every third day from the end of your period to the beginning of the next. That will cover it since sperm can live 5-6 days in your system.