Just keep an eye on the SUP events page and most of the demo days will show up there.
www.seabreeze.com.au/Events/All/All/Summary.aspx
Does anyone know if any manufacturers are holding Demo days in the near future ?
Depends where you are. Fanatic, Starboard and Naish have been running demos with shops across most of the country for the last 3 months. Most major cities and regional areas have been done by now. We put the Fanatic demos up on Instagram and FB at fanaticsupaustralia. I know Naish do the same on their social media.