There is no 'average' delay time, because of the many designs around. There is an average for each model, but every model is different from every other model. For a teetering system like early Bells and Robinsons, the delay is caused mainly, IMO, by the way the rotor moves independently of the fuselage, and thus it takes time for aerodynamics to move the fuselage after a cyclic input moves the main rotor plane. More blades generally means quicker response, and models like the AS350, BO105, etc, respond much more quickly, with little if any delay.