Implantation bleeding?

Nicole • PCOS and TTC for Years Unsuccessfully. Now we have transitioned into a "waiting family" looking for our miracle baby through adoption.
Hey everyone! so I' wondering how soon after ovulation you can have implantation bleeding? FF app says ovulation on day 9, so implantation 4 days after. Wiped and had very faint pink this morning, a few hours later it was pink with more brown. Ive had a backache and cramps for 2 days. Anyone experience implantation bleeding this early, or have any thoughts?