How to start editor script before releasing prefab on the scene view?

I want to be able to make a new object coming from tab Project through mouse drag interact to objects already in the scene.

The custom editor I created has its OnEnable method called as soon as the mouse enters the scene view, after I of course click and drag a prefab into it.

What I need is to drag a prefab from the Project tab and before releasing it into the scene, I cast rays into the scene.

Is it possible?