When to test?

Stacia

According to my calendar on glow, I am currently 13 dpo. Me and my so did the baby dance during ovulation, two days before and four days before ovulation. My period is supposed to start tomorrow but I experienced weird milky brown cervical mucus yesterday and now there is no sign of it. Could this be implantation bleeding if so, when should I take a test? I’m afraid it could just be AF but I never have spotting before a period. I need some help thanks!