We have a Corso from About Time Cane Corso. I believe they usually do their cropping before 8 weeks.
Laura and Richard drive all of their puppies to a vet in Colorado who does their cropping and does an amazing job... not too long and not too short.
I will say that aside from the aesthetic reasons there are safety reasons as well. Having 3 dogs who like to play hard as well as the fact that most Corsos play hard ear tearing is a very real possibility which nobody wants to deal with.
I also know that they crop ALL of their show and working pups.
I have heard more than one breeder say that having a Corso with natural ears while competing in shows has put their dog at a disadvantage... which is why often you will see dogs with natural ears stacked with their ears held up so as to show their head structure better.
Also as their ears are floppier than say a bullmastiffs ears they are even more prone to flying nun ears.
Here's a few pics of our boys cropping... personally I love they way they look. He is 14 months now. His were done at 8 weeks.