Waldorf Grade 3: Measurement and the Wheel of the Year

I can't say I slavishly follow any curriculum, but cherry pick what suits. Year 3 of the Waldorf curriculum is my basic skeleton, though. Inspired by a post on Little Nature Nest's Blog, we created a Wheel of the Year for the Southern Hemisphere that demonstrates the change of seasons as caused by the tilt of the earth in relation to the sun:

 Now I had been in a bit of a quandong about when exactly, say, Autumn starts in Australia. Friends said, "Autumn starts on the first of March". But I've used the Autumn Equinox, the 21st March (as my reference, I'm using the Moon Diary by Shekhinah Morgan and Jude Baderle). If I have my facts right, it's after this point that the days start getting shorter for us down under...