When to test after suspected implantation spotting 😕

A week before AF was due I had a few tiny brown spots followed by about 3 days of brown tinged cm (sorry tmi). Never in my life have I had spotting between periods! Now 4 days after the brown discharge has stopped and I am due for my unwanted visitor (about 15 dpo) I am testing negative with FRER.. Am I most likely out or is has anyone had a similar experience and got their BFP?!