Implantation at 12 DPO?

Gabriela • Hello I`m Brazilian. Came to California in 2010 for an exchange program, feel in love and got married. TTC #1 Since 5/14
I'm never early. Had some brown/pink ish spotting today. My AF isn't suppose to be till Friday (2 days). Is it possible to happen implantation that late? Tested yesterday and got BFN :(