hCG calculation date??

Hi there! I’m currently 8 DPO today, took a frer this morning but didn’t see much other than what I think was an indent

I’ve had some pink/brown spotting in my CM the last few days that I’m thinking is implantation spotting- I know it’s uncommon, but my body is sensitive to changes and spots during ovulation as well- but I’ve never had anything like this in my life before.

if this hCG calculator were to be true, would tomorrow (Sun Oct 23) be the first day I could potentially see something on a FRER?

Thanks!!