Okay ladies, it varies woman to woman. 
Implantation bleeding USUALLY happens 7-14 days after conception, USUALLY. that does NOT mean it can't happen 7-20 days after. I AM LIVING PROOF. 
For my first pregnancy, I did not experience implantation bleeding until TWENTY SIX days LATER. that's 26 days AFTER we had unprotected sex. I know because my husband is in the military so it was easy for me to know. 
The women on here are not professional doctors. They can give their opinion but I promise it is not always right. That's why it's an opinion. Not a fact. 
So YES. it is possible for all you women constantly asking this question & all you women saying its "ONLY 6-12 days" no. No it is not. That's a myth.