“ Stormtroopers, made when the Republic turned into the Empire, have NEVER been clones”
Almost correct. The surviving earlier clone troopers became storm troopers and were the trainers of human storm troopers.
But, yes, you are 99% correct that almost all stormtroopers were human draftees as the clone troopers (who aged at a faster rate) rapidly died off.
Yes, there was a short window. But they got squeezed out pretty quick.