If you are serious about keeping him for any length of time, please please look up proper diet for them. They are on milk much longer than you might think, and they have high calcium requirements (which nuts deplete). They can have seizures if their calcium levels drop too low. I have seen it too many times with people who have baby squirrels.

He is cute now, but when adolescence hits and his brain shifts into adult/wild mode, he can abe dangerous for you. Please reconsider taking him to a rehabber. He deserves a shot at a wild life.