Congratulations.
As soon as your child is old enough to listen to what mommy says. As soon as the child is old enough to understand that they need to wash their hands before and after, and that it's not ok to handle the snake without Mommy or Daddy's supervision.
Of course, this all depends on you as a responsible parent. My kids were raised with animals, and learned from the start that animals are not toys. They are our freinds and will be treated with respect. Some kids I've known were not taught this, and, in my opinion, should not be alowed around any animals, at any age, until they are.
Given that you are the responsible parent, and responsible pet owner, you, your child, and your snake can have a long and happy relationship together!
Best of luck!
GratefulFred
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GratefulFred