Informed consent. Neonatal or child's circumcision may only be performed after an informed consent has been obtained in writing from a responsible parent (mother or father) or guardian. Circumcision without written consent by a resposible parent or guardian does not meet the minimum required standard of care in the USA and should be reported.
Any age. A circumcision can be done at any age. However it's easier closer to birth. Also, there may be hypersensitivity of the head of the penis for up to 2 years after a circ if you are an adult.