Training and Development for first time managers. Proactive or retrospective?

When moving current personnel into a management position, is it important to train the individual before they are promoted to manager?

Does pre-emptive management training actually help an individual to prepare for a role in management. Some research tells us that pre role training cannot prepare the new manager for their role, but I believe that some training must give at least some form of aid to the new manager, in the form of tools and guidelines.

For example, my organisation does not give any L&D to any individual which is not directly related to their current position. Therefore, management training is not given until after someone is promoted to the position of manager. Is this too late? Is the star performer now out of their depth?

I am currently researching this topic for an assignment for my Diploma in Management Studies with London South Bank University and would appreciate any feedback which can be given.

Many thanks

Kevin