14 days before your period is due..eg.. if ur next period due 23rd april then u shud have sex from the 9th april till 15th april..u can buy a home ovulation kit from a pharmacy and use one every day from 9th,it will tell u if u r ovulating then..

what if ur not sure when you'll get your next period. i used the online calender and thats where it told me that i will get my next period on the 23th of april, it aslo told me that i was gonna get my last period on the 26th of march but i had it on the 23, so what should i do ??? plz helpppp!!!!

well buy home ovulation kits..there cheap if u go to amazon website..pack of 50 for like £10...start using them from the 9th april like i said,use one every morning, it works like a pregnancy test so it will give u 2 lines if u are ovulating..when u get the 2lines, well..its up to u and ur man