Brown spotting/ implantation?

Kayle
This morning I woke up with one brown dot on my panties and so I went to the bathroom to see if AF was early, it's only when I wipe and it's brown no red color. 
We BD the week before, during and a few days after O. My period is due on October 1st, could this be implantation? 
How long should I wait to test?