Opinions please ladies

I know this gets asked a lot but I am 8 days past the last day i had sex it was in my fertle window according to glow and im a week and a half out from my period ( long cycles) i got some light pink spotting yesterday and asked if it could be implantation bleeding most said yes. Today its a dark brown which i know means it's older blood. I thought implantation bleeding was quick? Stories insit anything welcomed :)