Stimulation comes in many forms and the intensity of it (based on the athletes level/ability) determines the period over which the stimulus is optimal.
On the weights lecture series at the site store, this is discussed in detail and you might also find the Taper DVD helpful as well. There is also a series of discussions about this topic on the forum in many places.
A lower level athlete may benefit from stimulus immediately before his activity but a high level athlete would be adversely affected and their optimum stimulus could occur days out from their event/training.
I recently got feedback from a top level European soccer team that the training modifications and activation plan I suggested last spring was incorporated and is working and I could see on TV that team speed is considerably improved this season so far.
It would be better if someone from the team itself spoke but they delivered a huge upset recently.