1. An image forming apparatus forming a visible image on a recording medium, comprising: an input unit configured to input an external instruction to the image forming apparatus; a functional element configured to perform an image forming operation; a first control unit configured to control the functional element; and a second control unit configured to communicate with the first control unit, perform a process in accordance with the instruction input via the input unit, and output a return signal for starting the functional element required for performing the process in accordance with the instruction, wherein an initialization operation for establishing communication between the first control unit and the second control unit begins simultaneously with a start-up operation of the functional element required for performing the process.