The following needs to be completed for the event to appear in the event log:
Completed Mythshore (event).
Caleb found and given a place to stay in Bareshade's Old Barn.
You have to do the full moon mission until you reach the part of the mission where the witch offers you a way to try to cure lycanthropy, an area will be released in the forest near the MC's house called Wolves Den, there is a beta werewolf, getting close to it the mission will begin.