Thanks for using the forum.
A woman's most fertile days are those surrounding ovulation. Ovulation occurs at about 14 days after the beginning of the period. Because every woman's cycle is different, this is an estimation. It can actually occur during days 13-16. The ovum is viable for fertilization for 12-24 hours after ovulation and sperm survives 3-5 days after ejaculation. To have the best chances of getting pregnant it is recommended that you have sexual intercourse 2-3 days before and 12-24 hours after ovulation.
There are several methods available to track your ovulation and menstrual cycle. You could track your cycle over several months and estimate when you are most likely ovulating. There are also over the counter ovulation tracking kits sold in pharmacies. Once you have a good idea of what days you are most likely to be ovulating you can plan to have intercourse 3 days before and 3 days after the estimated date. This will help to ensure the egg and the sperm meet while both are viable.
I hope this helps. Good luck!
Cathy