A few years ago I tried to teach my almost-three-year-old how to play Robot Turtles. Robot Turtles is a lot of fun for the kids. Will it help them with programming? I can't say.
Both my sons are into Minecraft now. I started programming at age 8... my oldest son is 7. So time will tell soon (assuming he even follows in my footsteps).
I started with text-based games in BASIC (like Batman-themed Choose Your Own Adventure). I recall the first step was understanding what a variable is and how to use it. (e.g. ask "what is your name?", capture the response in a variable, and then build the story with the player's name and other choices embedded in the text)
Don't worry about algorithms at that age.
If he shows interest in programming, I would start him on very simple JavaScript in jsfiddle.net. React + Redux can wait a few years ;)