Always wait until 12-14dpo, at minimum, if you want to an accurate result. While implantation can happen anywhere between 6-12dpo, approximately 80% of the time, it occurs between 8-10dpo. Also remember that it takes 2-4 days after implantation for HCG to rise enough to be detected on a home pregnancy test. Taking all of that into consideration, your best bet at getting a positive is to wait until 12-14dpo.