When does implantation bleeding happen

Well let's see. My fiancé and I had unprotected the. November 24th. The glow app said I was 22 percent likely to get pregnant. Well last night December 1stwhen I wiped I noticed a very small but noticeable drop of blood on the TP. It wasn't much but a faint drop. My question is could that have been implantation bleeding? I'm supposed to start my period on the 10th of December.