How long does the soreness stay after a circumcision?

It varies. It depends. If it's a child, i expect no soreness soon after circumcision in the same day. There may be some soreness when you change his diaper, but pulling on the scab. In adults, if you carefully change the dressing, there should be no major discomfort past that associated with the procedure and immediately thereafter.
Varies age+technique. Newbiorns appear painfree within minutes of procedure. Length of time soreness lasts in prepubertal boys depends on amount of postoperative swelling and activity. More swelling, activity or sutures used longer sorenaess lasts. Postpubertal and young men may have protracted soreness especially with erections + activity. Ativan (lorazepam) is good to reduce erections, anxiety and help with sleep.