The Witches didn't just sit in their camp once the monsters started to move out to the west. They were actively herding them, searching for villages.
Wolfe had heard that they had captured at least one scout, so they likely knew where a few villages in the region were, and he wasn't willing to let them get away with simply running over them quite so easily.
The locals should have some magical ammunition with them as well, and he didn't want that getting into the hands of the Witches this early in the game, so he made a mental note of where the witches were headed, and picked a group near the middle to follow.
On their current course, they would come across a village in a few hours, despite the slow pace of the monster horde.
The villages all kept a night sentry out, so Wolfe raced ahead of his chosen group to warn the locals that there was a Monster Tide, led here by the foreign witches, coming their way.
