So my question...would I be correct in saying that there has never been a time, even a single day, that the WTS wasn't preaching something, something they themselves concluded as significant, that has since been changed?
No no no no - you don't get it. See, that was old light. It wasn't untrue at the time. It is of course untrue now, but what they teach now will remain true until new light make today's new light old light. Got it? Sheeesh, such a simple thing