How soon?

Brittany • Stay at home mommy to 2 wonderful boys 3 & 4. Married to an amazing man. Love my family!
My husband and I have been TTC our 3rd child. AF visited last on June 19 my next visit from her is due in about a week. According to my calculations I ovulated on July 3rd. We had sex each of the 4 days before that. I took a HPT this morn just to see if I could tell anything yet. But obviously it too early. I've been cramping some and feeling sick. I wanna know how soon I can take a HPT before my AF visits?