The light coming on is not bad but it is an indication that you need to have them replaced. Could it wait a few days? Sure, but I wouldn't push it too much. Why? Well, if you wear the pad down to the rivets that hold the pad to the metal plate that rivet can grind into your rotor and triple the cost of your brake repair. Not to mention that less pad surface means less braking and that is not good if you are coming down one of those SF hills.
