He'll be lucky to not be able to recall it.
I don't recall much from before the age of four, but I had colic and pneumonia quite often before turning four.
If I do recall anything, it's images and feelings but nothing specific enough to say "Ah-HA!" about.
I on the other hand, remember a few things from before I was 4.
I remember sitting on the steps of our old house, playing with the
railing spirals. I couldn't even tell you how old I was. I also remember
sitting in front of our fireplace, I remember loving it too. We used to
have a Gumby figure sitting on the frame above the front door. When
someone would walk through & close the door, Gumby would attack.