You can easily tell when a light is going to change, simply by checking the crosswalk indicator. If DONT WALK is blinking, the light is about to change.

(That said, some lights with low traffic in one direction are programmed to get ready to change at a moment’s notice, in case a car pulls up, but most aren’t. So in that situation all you gotta do is check to see if a car is waiting for green if the crosswalk is blinking, to determine whether or not it’s going to change.)