Some women can ovulate early in their cycle
begins on the first day of her period), like about day 8, which would be June 25th. If you had sex today or tomorrow, your sperm would still be in her reproductive tract for three or four (some say five) days. Then just have sex every second or third day, until you're past day 16 or day 17.
A typical period is supposedly 28 days long, and ovulation happens on day 14 (starting on the 17th, count out two weeks).