An image forming system includes an image forming apparatus and a postprocessing device. The image forming apparatus includes a first communication unit, a paper feeder, and a first control unit. The postprocessing device includes a second communication unit, a postprocessing unit, and a second control unit. The second control unit obtains a first time to perform the postprocessing and a second time to transition to a performable state configured to perform the postprocessing. The first control unit obtains attribute information necessary for the second control unit to obtain the first time and the second time. When the second communication unit receives the attribute information, the second control unit transmits information indicating the first time and the second time. The first control unit controls the operation of the paper feeder based on the information indicating the first time and the second time received by the first communication unit.