From https://www.earthhour.org:

Switch off & Give an hour for Earth this Saturday, March 23rd at 8:30 pm your local time. Together, let’s create the Biggest Hour for Earth!

The Worldwide Fiund for Nature (WWF), 2024 website main page headline.

We participated.

The thing is, if you want to save energy and set a trend it doesn’t really matter when you do it, as long as it’s done.