The best time to do a reality check in the waking world is when something out of the ordinary happens, so that you stop and seriously wonder if you're actually dreaming. This is just a way of making something weird happen to make your RC more effective. If you're sitting in an adjustable chair that rocks back and forth, look out of the window at a tree or buildings or something. They'll bounce around in your eyes like the ground is moving, a perfect way to check if you're as awake as you thought.
