When to test?

So, me and husband are TTC. We just started this month really working on it. The other night my husband (who is certain we are pregnant by the way) goes and buys a test for me against what he wants (because he is so sure). I tested Wednesday morning the first test came up with a ? sign, and so I did it again and it said no. I was 6 dpo at that point, now I am 7 days away from AF. Did I test to early? Is there still a chance we are pregnant? How accurate is a test before you miss your period?