We don't need a test environment until after launch

If you use your production environment for testing before launch you have two problems to manage.

Firstly as soon as you go live you do not have a test environment - arguably when you need it the most.

Secondly when you try and retro fit your test environment you are trying to build it to match a moving target in production - which has a tendency to have already diverged from what was defined.

If you build your test environment first - you can find out the problems of building at a smaller scale, and use this as a dry run for your production.

It's easier to establish standards and methods for system builds on a smaller scale.

I've seen a live environments where of 7 application servers all 7 were different builds ... and to add an eighth the operators would pick the "best" one to clone - as that was the only way to create a new one. But of somewhat unknown provenance.

Deployment methods and processes affect system stability, security and disaster recovery or continuity plans. It's as essential to develop and test those as it is to test the application itself ...