ceiling cloud calculation/design?

Hey guys, I'm designing a small basement studio. I currently have my wall angles and soffit angles figured out, but what about the ceiling? I see a lot off guys mounting ceiling clouds to catch the first reflections comming from the speakers. I already planned on creating an absorbive front wall with soffit mounted adam a 7X and absorbive soffit wings. but is there a way to determine the angle / size and density of the cloud? I added the basic layot of my current room design. ceiling height is only 2,10m or 6,88 feet. Any advice / pointers welcome! thanks!