From personal experience assisting in many of these operations,
From personal experience, mine was done when I was 5 or 6 and done surgically while I was anesthetized. I vividly remember being scared to death of the pre-op set of beds before I went into the actual operating room. HOWEVER, the pain of recovery was memorable enough, as well. A few(?) days later, when I was in first grade at school, I had needed to pee. I had gauze bandages around "me" but I was embarrassed enough from the pain in "that" area that I had gone into an enclosed stall. A boy had peeked under the stall door to see why I was crying and was astonished to see why. He freaked.
Those are the two traumatic memories I have of my circumcision: fear before and embarrassment afterward. I only have a dim recollection of the pain other than I know that I did have pain.