The actual video editing process usually begins once you have finished the film, though with certain types of films like experimental films or documentaries you may start while still in production. The first step of the actual editing part is to put together a rough cut. This video editing rough cut may have some transitions, effects, and music, but generally it is the rough cut of the story and clips that you are going to use. This is what you are then going to show others for input for further cuts.
From here you are going to edit down your rough cut, cut out different clips, and smooth up the overall film. You want to get it into a tighter place where it will look more like the final product. This should be after you have taken critical looks at the rough cut and even after you have shown it to others for feedback.