Many triathletes train early in the morning. Some train early in the morning prior to their kids waking up, some because that is their free time prior to going to work and others because they are trying to fit two workouts into the day and the early morning workout allows sufficient recovery time prior to their afternoon workout. Whatever the reason you can be sure you will most likely be sharing your swim lane with another triathlete in the morning. You can also be sure that they had to make the same decision as to what to eat prior to training.
After a good night's sleep we most likley haven't eaten anything for approximately 8-9 hours. This does not mean that our muscle glycogen is depleted though, because it is not. However, we do deplete a good portion of our liver glycogen while we are sleeping and this in turn means that our blood sugar is low. Therefore, if we are going to begin training within one hour of awakening we simply need to refuel with something small that contains carbohydrates, and maybe a small amount of protein to keep us satiated during our workout.
I recommend having a glass of water immediately upon awakening to facilitate hydration. I also recommend eating immediately as well, and then going about getting yourself and gear ready to head out. The key is to keep it small and simple and to choose foods that will quickly get into your blood stream.
Some recommendations include:
1 clif bar
1 serving of cashew yogurt with some fruit such as a banana
2 pieces of bread with jelly
2 frozen waffles
breakfast cereal and soy milk
1 gel and a bottle of sports drink
1 original LaraBar. This happens to be my personal favorite. Original LaraBars are made with simple ingredients and are made with dates which contain glucose, sucrose and fructose. Some would argue against them because some of the bars can contain as much as 5 grams of fiber, so experiment and see what works best for your system.
Don't overthink it, don't overindulge, but be sure to get something simple in your system prior to heading out the door to maximize the quality of your workout.