Form a vision, then build the team. Not the other way around.
A team without a vision is not a team. It is a group of individuals pursuing their own objectives. Some of these objectives may overlap, but the group ends up pulled in multiple directions.
A vision aligns these individuals. It focuses them around common goal. It provides a cohesive direction to gather around and a solid foundation to build upon. A vision helps build a team.
Form a vision, then build the team.