My son will be born in about a month, when is the best time to circumcise him?

Maybe day 2, but...: Circumcision is unnecessary if normal, adequate hygiene is done. Boys are born complete, finished, and perfectly fine (except for the few unlucky ones with birth defects). Circumcisions are done for religious and cultural reasons, but the procedure does permanently change the genitals, so parents should think about it and talk about it before doing anything to their normal little boys.

When stable: There is no urgency but it works out better for the staff & doc if it is done when its convenient for all concerned. This is often the morning after they are born. Some delay may ne needed if a baby ends up premature &/or the family chooses an office based procedure but if done within the first weeks the newborn procedure is possible & healing is fast.