AF due 3/18

Hi I'm on month 2 of ttc and I've found my self to be test happy. I was on birth control for almost 2 years. When is the earliest everyone test? I have been testing 1 one week before AF and I Don't Know if that to early? I had a miscarriage 6 years ago and tested 2 weeks after conception (first time having sex so I knew conseption day) now that I'm tracking my ovulation not sure when to test with a good accurate result. I know at home test aren't 100% but I still am curious.