How soon to test?

Lauren

I had a positive OPK the 17th, with what I hope was implantation bleeding on the 24th. (Light brown spotting only when I wiped which didn't last). The ttw was killing me and I just took a hpt which was negative as far as my eyes could see but AF not due for another 3 days.....how long after implantation did you get a b fp? Should I accept this wasn't our month or keep hopeful and retest in a few days?