Implantation bleeding

On days 8 and 9 dpo I had mild cramping. I was reading about implantation cramps and bleeding. I did take a test on 9 dpo and it was a big n. So I just let it go. Today is 12 dpo and I had a light flow of dark/ old blood. I have been told it is best to test 14 dpo for a true read. My main question is have anyone else had the same type of symptoms with obtaining a positive result?