Creamsicle is an interesting one and something that was debated in Foundation Genetics for a bit and we feel there are a few ways to get to a Creamsicle. They all have 2 main characteristics WP or White pattern and an orange “creamsicle ice cream” coloration. So this particular morph although somewhat subjective should be reserved for the highest standard of classification. 
No history yet.
Genetically the Animal is always going to be Yellow base, WP, and Hypo. Modifying genes like line-breeding or Tangerine can be used to turn the Yellow, orange like a creamsicle. The White or Cream pattern and dorsal color however should be light cream to paper white. With paper white being the best of the best. If the animal is cream there is a chance that that pattern color may turn yellow with age, especially if tangerine is used to turn the yellow base orange. 
Too many people call an animal creamsicle just because they see a 2-tone orange and somewhat cream to yellow distinction in color. 
The subjective genetic part of this phenotype is that full coverage animals may look creamsicle but the black or lavender coloration that shows through in some areas like the cusp of the front legs or under the chin should disqualify it from getting the creamsicle title. The other portion is that some line breeding practices have yielded orange base animals and tangerine was not used to create the orange base color. Therfore, genetically there are a few routes one can take to produce consistent creamsicles. 
No known proven lines