2 hours is sufficient time. It really depends on the protein. Some proteins take longer to be digested. Whey protein takes the least amount of time to digest and is generally digested and readily available within an hour or so. Casein, milk proteins, etc all take longer, that is why they are better for PM (night) formulas. Chicken, tuna, etc may take 2-3 hours before they are digested.
PS: Karma is always welcome here!