Fortunately, cyclists can eat shortly before a ride with fewer fears that food will settle uncomfortably in their stomachs - probably due to the lack of jostling that occurs for example with running. So it’s not too late to prepare for your first day.
If you haven’t exercised for several days, your muscles are probably glycogen loaded and would handle several hours of steady exercise without any breakfast at all. But anything you eat now will extend this fuel in your tank to prevent a fade later in the day. The same is true of a good midmorning snack and a midday lunch stop.
Carbohydrates are best, but don’t worry about a little butter (fat) to make the meal enjoyable - dry toast just doesn’t do it for the ambiance and a good state of mind is just as important as good nutrition for most recreational rides. Complex carbohydrates (fruits, breads, pastas) are preferred to the simple sugars of fruit juices and sugar drinks. The latter are a great energy booster when you have the bonk, but can cause swings in the blood sugar when taken before the ride and then be gone from your system 30 minutes later while the complex carbs are digested and absorbed more slowly providing a steady energy supply to the muscles.
And when you’re done for the day, take advantage of the body’s preferential treatment of carbs eaten within 4 hours of exercise to restock muscle glycogen reserves. It’s insurance for a good ride tomorrow. And if you plan on going for the advanced 75 mile ride in the AM, be sure to eat a good dinner and even a late evening carbohydrate rich snack to assure that you’ve maxed out that muscle glycogen.