AF on its way or not?

Normally I spot 3-4 days before AF shows up. This time it is 7 days earlier than when AF is expected to show on the 20th. Ive been wearing a tampon and theres only blood barely to cover the tip. Started off pink to brown to red. Is AF coming or is this IB? Took HPT and all were BFN. Today is 12 DPO