Pit lane start

For pit lane starts, when does the pit lane exit light turn green? Is it after the leading rider passed the end of the pit road or after the entire grid passed the end of the pit road?

For pit lane starts, when does the pit lane exit light turn green? Is it after the leading rider passed the end of the pit road or after the entire grid passed the end of the pit road? http://ifttt.com/images/no_image_card.png