Pregnancy

So I’m due for my period but nothings come yet resulting in me being late, I’ve had a lot of unprotected sex this month I’m not on any protection he pulls out , I’m spotting light brown and have been for 3 days barely any cramps at all this is very unusual for me as I’m a heavy bleeder and I’m not spotting heavy at all it’s mainly when I wipe and comes and goes it’s not consistent if that makes sense . My question is if this is implantation bleeding would it occur now or should it have earlier ? I’ve tried looking up when implantation bleeding happens but can’t find much info.