Should I join the Windows Insider?
Windows 10 version 2004 (build 19041) was released on May 27th 2020.
How long should I wait for that update to be released if I don't want to join windows insider?
As of May 27th 2020, you are not required to join the Insider Preview program, in order to receive a WSL2 compatible build (19041 or newer).
Important to point out that there isn’t any build of Windows 10 version 1909 (Insider Preview or otherwise) that supports WSL 2. So it is impossible to run Docker Desktop on Windows 10 Home if you are not running Windows 10 version 2004.
Last year we announced that Docker had released a preview of Docker Desktop with WSL 2 integration. We are now pleased to announce that we have completed the work to enable experimental support for Windows Home WSL 2 integration. This means that Windows Insider users in 19040 or higher can now install and use Docker Desktop!
To get started with WSL 2 Docker Desktop on Windows home today you will need to be on Windows Insider Preview build 19040 or higher and install the Docker Desktop Edge 126.96.36.199
Source: Docker Desktop for Windows Home is here