Creamsicles are amels that have emoryi blood in them. It's basicly a corn/great plains ratsnake hybrid. Some people have mixed emotions on the hybrid, but either way they make for beautiful creatures.
So far as the details, ie amount of emoryi blood in the snake, i'd ask the breeder. I'm no expert by far, but i'm sure Rich, Don, Kathy, or maybe some of these genetic wizards floating around the site could help you out with the exact specifications of what qualifies as a Creamsicle.
As for the original question, i'd say in general....yes. Yellows tend to come in later. Bloodred's patterns and colors diffuse into a uniform red (idealy) and okeetees tend to get much brighter as they grow from hatchlings to adults. Other morph's colors develop as the snake gets older.