In calico yellowbelly's, the white never really seems to creep up. Here's one that's about 2 months old with some of the highest white I've seen in a calico YB:
They usually just hold that gradient blushing on the sides and crazy pattern near the belly.
The Calico that produced the clutch doesn't have a lot of white. More like white speckles through out her patter. I didn't know if the babies hatch white like a pied or the color comes in over time.