Hoop coop [and grass]

When the chickens are full grown, I'll start hauling the hoop coop around the yard. They'll have day access to a paddock. But how frequently will the hoop need to be moved in order to keep the grass/weeds healthy (ie: not dead and able to spring back with a bit of sun). My plan for until they are grown is to park the hoop house wherever I want my compost pile to be.

They confined to the coop? How many chickens, what's the size of their run area?

Duh, that would be helpful, wouldn't it?? They're 4 weeks old, 8 of them. I'm planning on keeping them mostly confined until they're full grown. This would be their coop/run for now. My husband is thinking the tarp blocking the sun + chickens will kill all the grass in short order and I realized I haven't the faintest idea what will happen.

When they're nearly full size I'll add a run/paddock. Still working on the fence material. Hoping it'll be around 250 sq. ft., though.