That's a tough one to answer. I should tell you to wait until at least 12 DPO to test, but then I'd be a hypocrite, lol! I have gotten too anxious and tested as early as 9 DPO before. I say, if you have a ton of tests and are prepared to expect the early ones to be BFNs, then test whenever the urge hits you. Otherwise, I'd wait. It can get costly and once the POAS bug hits you...it's hard to resist!
How many DPO are you now?