The time you can concieve is 11-14 days after you start your period. From the day you start, count 11-14 days. That is your most fertile time. If your periods are regular this applies. But if they aren't, you aill have problems. I recomend condoms or the pill. If you don't want to become pregnant steer clear of the 4 day period or to be really sure wait 6 days. Hope this is some help.