I would start with something less abstract, more concrete to start. I have a 4 year old who picked up the ability to program this simple mouse to navigate the maze and find the cheese. If I try to go too abstract, you can see the eyes glazing over.
I was at a steam fair last weekend, and they had the OhBot, a programmable robot face, on display. It is programmed with what appeared to be a version of Scratch. You could control the head, mouth, and eyes with the track pad and keys. Kids were really into that and there was quite a line at that table.
Thinkfun also has a good board game to teach programming logic called Code Master Programming Logic Game.
If you really do want to go a more abstract route, I would start with the Python for Kids book by Jason Briggs. Once he gets through that, get the Python Crash Course next and work through the 3 problems in that book. It has one where you make a Django app with a user login.