Time evolution of the shock shell mass (top left), shock radius (top right), shock velocity (bottom left) and optical depth of the shock shell (bottom right) for several well-fitting models. The adopted model parameters are the same in Fig. 4. We excluded the late-phase data (t ≳ 200 d; grey hatching) from the light curve fitting. The black open circles in the top right panel are the blackbody radii of the optical component from the two blackbody fitting in Paper I.