When does implantation bleeding begin?

And how early can it start? Idk if im ovulation spotting or if it’s implantation and im terrified. I’m in my fertile week right now and yesterday I had right hip cramps and today I saw light pink in my discharge. Period is due in 3 weeks and I’m supposed to ovulate Tuesday. I had protected sex last Saturday, 2 days after my period and he wore a condom and didn’t finish in or near me