- Add a Clock block to track simulation time.
 - Use a “Compare To Constant” block (>= 0.3) to generate an enable signal once time reaches 0.3 seconds.
 - Feed this enable signal into the Enable port of an Enabled Subsystem.
 - Inside the Enabled Subsystem, keep the desired system.
 - Connect the original signal to the input of the Enabled Subsystem.
 



