As to the transition lenses, it armed with chemical compounds that spring to action under ultraviolet light. So the transition lenses darken even on cloudy days to keep out those damaging rays. Then if you step in to indoor, it will simply return to clear. So if you want to make them change color faster, you could go to the place where have strong ultraviolet light.
Moreover, the speed at the color change also depends on a number of factors such as heat and the material of the lenses. Normally, it takes between 5-10 seconds to go from dark to light.