How much should a 8 1/2 wks old mini schnauzer eat?

My son and his wife just got a Miniature Schnauzer pup and she's 8 1/2 wk old and she can really eats a lot does anyone no how much she should eat at this age. They plan on asking the vet when they go in next sat. but would like help now if anyone no's. I've never had this breed but in just a short time she has eaten almost a cup of food and that seems like a lot to me for such a small dog.