According to the New Testament, after how long an interval did Jesus promise to return to earth?

Answer:

Jesus' alleged remarks about the parousia, that is, his promised second "presence," "arrival," present a problem for Christianity. Some of his statements anticipate a quick return (Matthew 10:23; Mark 9:1; John 14:3, 21:22-23), other comments are less sure and suppose an indeterminate interval before the return (Matthew 12:31-33, 24:50, 25:13; Mark 13:35-37; Acts 1:7); and in one instance Jesus is reported to have said he does not know when he will return (Mark 13:32).

Jesus made none of these comments. These various statements reveal that the myth of the "second coming" was explained in different ways as the interval following Jesus' death lengthened.