Most OPK will give best results when you test after lunch. This is when the hormone in your urine peaks.

I prefer you guys wait till you will get a for sure positive result. So 12-14 DPO. I believe testing too early causes people nothing but heartache, both from false negatives that will later turn positive, and also from chemicals which happen to all of us over the course of our lives and the vast majority of the time don't mean anything negative for your fertility, but people tend to panic and obsess over them.