Your baby will show you he is hungry in any number of ways. His breathing will change, his eyes will move beneath his eyelids, he will move his arms and legs, stretch, bring his hands to his mouth or face and make sucking motions. These are all signs that your baby is hungry. You will recognize them more easily if you keep your baby close to you.
There’s no point waiting for your baby to cry or get angry before starting to feed him. Changing a diaper to wake a sleeping baby is sometimes a good idea, but is best avoided if your little one is very hungry. Do whatever works best for you.