Post-AGB time scale for the star to reach T = 10⁵ K is plotted against core mass. The filled circles show the Blöcker model set. The upper long-dash line (blue) correspond to the interpolated formula of Eq. (2), and the lower long-dashed line (magenta) is for the accelerated evolution of Eq. (11). The solid line (with squares) shows the envelope-mass parametrization of Sect. 3.5, and the short-dashed line (with squares) shows this parametrization with envelope masses at the end of the transition phase reduced by a factor of three.