Egg whites as I understand it are digested in about 30mins but nearly all of the aminos in them and protein are available for bobybuilding the muscles for I think up to 3hrs or slightly more.
I usually have a whey shake upon waking 6:30am, followed by oatmeal at 09am, followed by 6 to 7 egg whites at 11:30am, lunch at 1pm etc. and so on unitl a whey shake with flax before bed.