Idea for Rumble's E (rito pls)

So I had an idea for Rumble's Electro Harpoon. Since the ability utilizes a charge system (max 2) how about making it a two-part stun. ex. If you hit a champion with the first E you have a 2/3/4 second window to hit him again to apply a 1.5 sec stun I don't have any idea how Rumble could balance this in his kit but I think it would be a good addition to his early/mid game and pick potential. Poll below -->