In Jenkins Configuration-as-Code Plugin the initialization may happen in parallel with Job loading. It may cause various race conditions in the plugin, see https://github.com/jenkinsci/configuration-as-code-plugin/issues/280 for more details.
In order to address this case, I propose to create a new Milestone between EXTENSIONS_AUGMENTED and JOBS_LOADED. It would allow some plugins to handle extension-based functionality, e.g. to do some Jenkins preconfiguration BEFORE it starts loading jobs.
I would call it "PRECONFIGURATION_COMPLETED" or so.