I figured out the answer: use a module. Even better, I asked bard.google.com for additional inspiration:

Imagine writing a simple three.js spinning earth or globe. Since it takes time to load, load it as a module. While it is downloading show the text "loading...", then show the spinning globe when ready.

And the answer was amazing!

This seems like the winner...check out the easy peasy answer on Stackoverflow !

https://stackoverflow.com/questions/35575065/how-to-make-a-loading-screen-in-three-js

I'll have to give this one a try for sure.