What you are/AGY was referring to is the pre-completion...

What you are/AGY was referring to is the pre-completion commissioning
On-site commissioning happens after practical completion which didn't occur until beginning of 2023

How on earth can you put the plant to work and try it if you haven't finished constructing it?

Come on rob, it is not that difficult to understand. Ask an engineer for help.

1. Phases: Construction commissioning can’t happen all at once. It’s a process that requires planning, implementation, review, and more. It also happens throughout the life of the project and looks different at each phase³. The common phases include:

   • Pre-Construction Checks and Preparations: This phase holds the beginning of the commissioning process. Some of the most important facets of the process occur at this phase³.
   • Execution: On-Site Activities and Checks: After the pre-construction checks and preparations process, the Cx team will begin the on-site activities and checks³.