When can I close my laptop lid during shutdown?
As soon as the shutdown procedure starts you should be safe to close the lid.
normally you have to wait for laptop to do a complete shutdown, but you can change this when you click the power options and set what the lid will do when closed (set it to do nothing, that way, it won't hibernate or sleep, it will just do whatever the laptop is doing before you closed the lid (shutdown if your shutting it down, play music when you're playing music with it))