When can I test???

Jade • TTC since April 2015 for baby #2, have a 5yo girl, have been with hubby for almost 8yrs, hoping to be blessed again :)
I had AF 4/8 and got positive OPK on 4/27, and AF is due again 5/6, so when can I test? Since I would only be 9dpo on the day AF is due... Would a preg test be able to pick it up at that point?