Most HPT's will give you an accurate response at around 10DPO. I got a +ive HPT with the crystal clear digital at around 9 or 10 DPO when I was PG with DD. I had no symptoms at all but did an HPT simply because I was TTC and TTC and being a compulsive HPTer go hand in hand! I couldn't confirm the sensitivity of it though. Do keep in mind that it takes 6 to 10 days for implantation to occur though so I would be reluctant to test (and expect an accurate response) before 10DPO.

MG