So how long after ovulation can implantation bleeding occur?

What does implantation bleeding look like?

Af was due three days ago, nothing. Bfn Sunday, Tuesday, and this morning. Still no af. Today after my lunch break I went to pee and then there was a little blood when I wiped. So I grabbed a tampon and assumed my period started. Im now getting ready for bed and when I took the tampon out, it was barely full. Went pee and wiped, very little blood again.

My cycle is 28 days, Sunday to Sunday. But today is obviously Wednesday and I'm barely bleeding. I don't know if I'll continue to bleed tomorrow like a period or if I was "spotting" which is not normal for my cycle. Thoughts?