A method is disclosed for determining a measurement start time for an imaging measurement via a medical imaging system depending on a course of concentration values of a contrast medium in a monitored region of an examination object over time. The method includes detecting the concentration values of the current concentration of the contrast medium in the monitored region at different successive detection times； determining a current examination-specific accumulation model curve on the basis of a course of the concentration values over time； and determining the measurement start time on the basis of the examination-specific accumulation model curve. A method for controlling a medical imaging system, a control device and a medical imaging system for implementing the method are further disclosed.
