I have been caring for my California King for 12 years, and I have been musked only a few times at the most. I think that you really should focus on how much time you plan on spending with the animal, rather than worry about the possibility of being musked. I have not been musked by my king in over a decade, and I regularly handle him for hours at a time. I don't believe the musking is an age thing, and something that they "grow out of". I think it has more to do with the animal getting used to being handled and you learning what the animal tolerates before being musked.