Simple, the moment he/she turns 18.
If you don't force the child to visit the other parent, you can be held in contempt of court. As your final order states, you can be fined ($$) or jailed for violating a court order.
If there is a reason the child should not visit the other parent, then MODIFY the visitation order.
For example, Mom is doing drugs and is homeless. Then go to court and ask the court to modify the visitation order.