Those who had implantation bleeding

How soon after did you get your BFP? My period is due in 2 days. Yesterday I had brown mucous discharge (very very weird for me). I thought my period was starting so I put in a tampon but the only thing that came out was some snotty discharge with some brown in it. And that’s it. Nothing else now. No bleeding or anything. When I check my cervix, i get a bit of yellow EWCM. No idea what’s going on. I tested with FRER today and it was a BFN.

Am I out? Anyone experience anything similar?