It depends on how long your cycle is and when you ovulate. Women with shorter cycles can get pregnant pretty soon after their period, if you have a longer cycle you tend to have a few days "grace period". The first day of your cycle is the first day of your period. Most women ovulate sometime between day 12 and day 22 depending on length.

I would just think about the longest time you've ever had between periods and watch for pregnancy signs. Good luck!