Period came 4 days early ! Could this be implantation bleeding in disguise ?

Sherita

my period was supposed to start on the 15th of this month . but it seems to have started on saturday . It started out light with barley any color...and as it got way later in the day it was still barely anything there, just when i wiped. but the next morning i woke up to my underwear soaked. my period has never come 4 days early. could this be implantation bleeding instead? has this happened to anyone?