Scrapping a Car before the V5 has arrived?

Anyone ever done it? Know what the process is? In my experience, to scrap a car, you need to complete the CoD on the V5 and shoot it back to the DVLA to say the car is ded and gone. Now if I buy a car, strip it for parts and have it ready to be picked up before the DVLA manage to get a new V5 to me, what do I do? Do I need to wait until the V5 arrives before the car gets collected, or can I fill the form post-humous once it arrives?