Implantation or period?

Ladies, I'd like your opinions please!

Basically, I think I might have just started my period. I was suppose to be implanting around this time (if pregnant) and period isn't due till Monday but I've just had, what I think is a bleed. I wiped and it was pink and then it seemed to increase a little bit and then it came out brown after a while. There isn't a lot though. I've got slight cramps on and off but not a lot. Has this happened to anyone else and it turned out they were pregnant or is it AF arriving early? TIA