The beauty of the word "yes" in marker training is that you do not have to be ready to go with a high value food reward all the time. By incorporating some simple food chasing drills, you have the ability to mark a specific behavior at an exact point in time without having the food in your hand. You can then turn your high value food reward into a reward event. This not only allows you some leeway with your timing, but it also channels your dog's energy and builds drive for whatever activity you are training.