Hi, I Am 20 Years Old, And I Am Planning

Hi, I am 20 years old, and I am planning on getting pregnant but I have a problem, I have never tried to get pregnant and I don't really know how to go about testing, how long should I wait before testing? I had sex right after my period, and I don't know how long I have to wait. Take in mind I have irregular periods, in other words I never know when my next one is coming, I have tried keeping track but the dates are all over the place.