It depends on how I feel when I get up. Part of it, is that it's 5:30 in the AM. I can eat a Lara Bar, or a very small bowl of whole wheat cereal and almond milk, but I don't have time for that always, and it's a fine line between too little and too much, where my stomach hurts during all that jumping, twisting, etc. If I feel ravenous when I get up, I eat more. I wouldn't go out to ride on 5 almonds... this morning I rode 15.5 miles at the same time (it was already 74 out), but I had a Lara Bar. If I am going on a longer ride, that early, I eat a small breakfast and bring a big snack or plan a restaurant stop. Another issue is I don't want to have to leave the class to use the bathroom, and if I eat a lot, that will happen.
2015 Trek Silque SSL
Specialized Oura
2011 Guru Praemio
Specialized Oura
2017 Specialized Ariel Sport