How long for pigeon to have babies?

It depends on the kind of bird. Some that have long lifespans (eagles, penguins, albatrosses, large parrots) have only one or two young at a time and nest only once a year (or less often), while others that have short lifespans usually have many young at a time (quail, turkeys) and/or nest more than once a year (doves, some Songbirds).