I pretty sure it's only when YOU discover that Tech, which given the newly designed tech tree, can be awhile. When i build Stonehenge early, I hold off on Calender for forever. I mean, I have so many more techs before I get calendar.
The penalty is that you lose access to certain resources, as you can't build plantations, but with trade and conquest you can get others to suffiently allow for those losses. And the extra culture and Great People points just continue to grow, especially if you are philosophical.
As I said in my thread, I also hold off on Scientific Method when I have several Monasteries so I can keep my 30-40 % tech boost.