Is this spotting implantation bleeding?

Juliette

Today is Saturday and my chart shows I am 12dpo. Between 7dpo and 11dpo I have had barely there spotting, some cramps and breast soreness. Today there is nothing at all. Could this be implantation bleeding? Period is due Monday but should I buy an early pregnancy test? Some say they can detect up to 6 days before period. I may just be setting myself up for disappointment though. Please tell me your thoughts or if you have experienced something similar. Thanks!