15 DPO, negative HCG, spotting, could these be implantation bleeding?

Lauren

So I’m 15 DPO and I’ve had this, I had a miscarriage 2 months a go, I’m wondering if maybe I just ovulated a bit later than usual and this could be implantation bleeding today? When would be the best time to take a test, Friday perhaps? Not sure when it would show a positive if I was?