TSLint not working with CRA and TypeScript
I had to go through the same process figuring how to get TSLint and Pretter to work on a CRA + TypeScript project.
I created this gist with step-by-step instructions on how you can set it up accordingly.
The above solution, in a nutshell, is to make sure that you have the appropriate VSCode extensions installed and the appropriate dependencies in your package.json so your changes get tracked by both TSLint and Prettier.