To me it's on a case by case basis, the more animals you own the more you come to realize they differ, I have some that I have house straight from 6 quarts tubs to 41 quarts and others that I moved to 15 than 32 than 41, it really depends on the animal and how well he does.
This is something you learn as you go as you see your animal grow and learn his behavior and recognize whether the animal is stress or well adjusted to his environment.
Now if I was giving general advice I would say
6 quarts untill it reaches 250 grams
15 quarts until 500 grams
32 quarts until 1500 grams
41 quarts for anything over 1500 grams
Again depending on your animal you might be able to skip some step![]()