which comprises a plurality of devices including at least one of an image forming device which can print data in a storage unit that can store data of a plurality of jobs including data of a first job and data of a second job which is input after the data of the first job, and a sheet processing device which can execute a sheet process for a sheet printed by the image forming device, comprising:

a scheduling control step suited to set a schedule associated with a plurality of work flows including a first work flow that includes a plurality of process steps using a plurality of devices of the image forming system required to complete the first job, and a second work flow that includes a plurality of process steps using a plurality of devices of the image forming system required to complete the second job; and

an instruction step suited to selectively input a plurality of instructions including first and second instructions,

wherein the scheduling control step includes a step of setting, when the first instruction is input, a first schedule which is scheduled to complete the second work flow for the second job input after the first job, after completion of the first work flow for the first job, and a step of setting, when the second instruction is input, a second schedule which is scheduled to complete the second work flow for the second job input after the first job, before completion of the first work flow for the first job; and

further comprising a device control step suited to control, when the first schedule is set, the plurality of devices of the image forming system to complete the second work flow for the second job input after the first job, after completion of the first work flow for the first job, and to control, when the second schedule is set, the plurality of devices of the image forming system to complete the second work flow for the second job input after the first job, before completion of the first work flow for the first job.