A control method for powering timing, performed by a controller, includes: performing a delay modulation procedure when triggered by a delay modulation command, wherein the delay modulation procedure includes: after a delay duration has passed, determining whether a number of output voltage values of a number of voltage converters reach a number of target levels respectively, wherein the target levels correspond to the output voltage values respectively. The method further includes: if any one of the output voltage values does not reach a corresponding one of the target levels, increasing the delay duration according to a first default interval and updating the delay duration, and performing the delay modulation procedure when triggered by the delay modulation command again; and if the output voltage values reach the target levels respectively, outputting a power good signal to a central processing unit, for the central processing unit to perform a booting procedure.