Breakfast, most likely, given that you've just gone almost a half day without food. Really though, simply eating good food whenever you're hungry and stopping when you're not, even if that means eating 5 or 6 times a day, isprobably better. People get so caught up chunking their eating times into 3s that they may have an urge to overeat since "it'll be several hours until I can eat again!" Just chose to eat in a way that lets you stay un-hungry all the time without ever overeating.