How soon can i test?

Okay so I did some research and normally it says I can test as early as 6 days before my missed period. I'm eleven days from having mine and I'm kind of impatient. My fiance leaves for six months at the beginning of November and we really want a baby. How soon did you guys test? We already have a daughter but I didn't find out I was pregnant til I was 7 weeks. Help please.