Anytime. Most circumcision are performed within ten days of birth. Is there a medical or religious reason why you might consider it on a child this age. It will require some time of short term anesthesia and a more stressful period of healing for a child of 3. You might discuss options with your pediatrician.
Not a good age. Psychological studies have shown that genital surgery should be avoided between age 3 to 5 years.There is no problem before age-2-years, but later boys can be severely psychologically disturbed for quite a long time, frequently refuse to urinate for a long time after the procedure, even needing to be catheterized. You can reason & explain the operation to boys 6 years and older.
Yes, any time! Your local pediatrician or family doc should be able to fix you up with a surgeon (pediatric urologist) who can take care of this. Circumcision can be performed at any age but it is best to have it done sooner rather than later, since it is less upsetting for the child when it is done at a young age. This is a simple outpatient procedure with health benefits your doctor will explain.