Personally, I would say seven is a bit young to start introducing him to programming. I don't know what your background is and what you expect from him but my biggest piece of advice is tread carefully. He has quite a few years to become interested/fascinated in programming as well as mature the thinking and analytic skills needed to be a successful programmer. Pushing too hard or introducing it before he's ready could result in him getting a negative attitude about programming. My recommendation would be to hold off and wait until he's around 12 to actively introduce him to programming as a career/interest option if he isn't doing it already.
For full disclosure and as a point of reference; this is my business right now. I cofounded Mimetics Inc. (https://mimetics.ca/) to introduce and engage children in STEM (Science Technology Engineering and Mathematics). We've done over 16,000 students, from ages 6 and up with quite a bit of success in introducing kids to technology and getting them excited about it as a career.
I find that the best approach for introducing young children to program is having something concrete that they can program on with statements directly causing physical actions. This does not mean an Arduino or Raspberry Pi; I know there will be disagreements to this statement, but younger children do not have the manually dexterity to handle wiring or work with complex mechanical structures.
For a parent of a child younger than eight, I would recommend the Wonder Workshop Dot and Dash: https://www.makewonder.com/ The robots are quite a lot of fun for children and are provided with an iPad app that allows control and introductory (Scratch) programming.
As a father myself, I didn't actively introduce programming to my kids at all; they could see me do it and I was available for explanations of what I was doing and demonstrations as how things were done. Maybe a bit incongruous considering my current career arc, but the result has been my older daughter who's now taking Game Programming at college and a 12-year old that is having programming parties at our house with her friends.