He and his uncle have talked about how his uncle was helped by a fox, and meeting three animals and so gaining three animal companions is a classic. Another one is meeting strange men with odd powers like running like thought, but that would be more human clutter -- not that the animals would be nothing -- but then the rest of the story has to be determined by their powers. Animals can be helpful but aren't that constraining.
Meeting three old -- men, probably since he's a boy (and it's the girls who get to meet the good witches along the way), would be least constraining, since each one would just send him on, until finally one directs him to the place he needs to go.
On the other hand, he does have some idea. Unless he gets lost because of a storm at sea. . . .