The answer really depends on the size of jib, vehicle access to the set, and if there is more than 1 person building it. We typically request at least 2 hours to load-in, set up, and fax. Setup time for the jib itself may only take an hour, and then mounting the camera/lens, balancing the remote head, and tuning the remote head controls could take another hour. In scenarios that require parking permits, allowing an additional 30 minutes to an hour is recommended.
If the jib needs to be resized during the shoot, it could take up to an hour, depending again on the configurations involved.