You can test then, I tested at 10PIUI on our second try and got a +, although it was very very faint. However, if you get a - it could be false, it depends on when implantation occurred.
Maybe your spotting is implantation, perhaps...maybe you implanted later???
Good luck!
If you are pretty sure it is AF then why do you want to test and waste a stick. Instead I would save it for next cycle. If not, and you suspect it might be implantation, then I would wait couple more days to test. Because in that case it might be early to find enough hCG to get a BFP.
Either ways I recommend you to wait for couple more days to test. Wish you SSBD.
I tested early and got a dark line and I was 13DPO I would probably get at least a light one if I tested earlier than that...I hope its implantation for you... I had brown spotting too like around my pregnancy and it might be old blood passing out from the implantation that happened earlier.. either way I rested to make sure..
good luck to you :0) all the best.. sticky baby dust :0)