Implantation bleeding perhaps ?

Li

Yesterday I had brown bleeding which assumed was my period but lasted a few hours. I wore my pads all through the night and it is basically empty with only a brown spot mixed with cervical mucus

According to Premom I was 13DPO and my expected period day and according to another app I was 11DPO yesterday.

Could this be implantation bleeding? How soon after can I test to be sure?