That is too young. The person that sold him to you should know better, or he should get out of the donkey business. Make sure he has a pasture mate. Pasture mates are not just for companionship. They teach young equines important lessons on behaviour. They teach them about herd hierarchy, respecting space, discipline, etc. I have some experience in rehabbing horses that were taken from their mothers too soon and raised by humans. They easily become spoiled and dangerous. Just as a mother dog teaches a puppy things like bite restraint, an equine mother teaches her babies to not be too pushy. They become large animals that will walk right into and over a human without this basic lesson. Your donkey might not get very big, so it may not be as much of an issue. I would highly recommend that he have an older, gentle pasture companion to teach him. Donkeys can be obstinate. The little baby might be cute now if he comes up and leans on you. However, an obstinate bratty adult that literally pushes you and your kids out of the way can be dangerous.