Implantation bleeding?

Glow has me starting my new cycle in 9 days, kindara in 3 days. I am a clockwork 27 day cycle and am on day 23 right now. OPK peak last Sunday. Yesterday woke up to dark brown spotting. Ebbed and flowed in volume over the day but never more than a pantry liner used. Today is day 2 and if it is af, she is very unlike my typical cycles. Just asking for some advice because a lot of articles say it should be a few spots and last a couple of hours, but when you talk to people some say it lasted 2-3 days. Anyone else?