If you are trying for a girl then you should try 1-2 days before you ovulate and if you are trying for a boy then the day you are ovulating or right after ovulation. If you don't care, then try every other day the week of ovulation. I have four boys and am 21+6 and finding out sex tomorrow morning. I did several things this time to try and sway it for a girl, but we will see if it worked. Good luck!
The 4/5 days leading up to ovulation are your best chance. You can get pregnant anytime in you cycle though. The more you have sex the better your chances. Just relax and go with it. It can take months so best not to stress and try and enjoy the things you will miss out on when the baby is born