Use familiar carbohydrate-rich food, comfortable timing and training experiments to find what suits you.
Begin with familiar food
A pre-run meal should be something you tolerate, enjoy and can repeat. Many runners favour carbohydrate-rich foods with modest protein while limiting foods they know cause discomfort.
There is no universal menu or perfect clock time. Session length, appetite and digestion differ.
Test the details in training
Try meal size, timing and any during-run fuel on ordinary long runs before race day. Record useful observations rather than labelling foods universally good or bad.
If you run early, a smaller snack may be more realistic than forcing a large breakfast.
Medical needs are individual
Diabetes, gastrointestinal disease, pregnancy, allergies and other conditions can change fuelling needs. Seek advice from a qualified clinician or registered dietitian.