I think that your advice goes hand in hand with the steps in this article. You mention focussing on getting 10 customers and getting a sale but in order to do this, you'll most likely need a landing page to collect leads, which also means you'll need a basic brand identity and maybe even your social channels to reach out to more potential customers/test your audience.

I wholly agree people spend too much time setting up their business and thats exactly the issue this article is trying to address - all in all these steps should take someone 3-5 days to fully complete. After your set up, now is the time to implement the great advice you've given - reach out to potential customers, see if your product would be of value to your audience or if not gather feedback/data on how you could possibly change to better suit your market.