Implantation at 12 DPO???

Em

How likely is implantation at 12 DPO? This morning when I went to the bathroom I had a tiny bit of brown cm when I wiped and again later this morning. It’s only the faintest light brown and it’s only when I wipe. I had half a degree temp decrease this morning that dipped just below the coverline. Is this more likely to be implantation or the start of dreaded AF? I’m trying to stay hopeful!