Ok, I know things work differently in different states, but IMO there is a huge difference between preschool programs run in kindies/preschool and those run in long daycare centres. Does he attend a real preschool or just the daycare version? If it's just daycare, it might be worth getting him into a real kindy/preschool if you can.
I believe the OP is in NSW - and would need to check what sort of program that their daycare runs.

However for other readers:

At least in VIC - if the daycare center is an approved 4 year old kinder program provider then - the program offered is at least as good as a sessional kindy. I don't know about other states but here there is this attitude towards daycare versus 'real kindy' which is totally unfounded, the programs are subject to exactly the same guidelines and standards as any others and follow the Early Years Learning and Development framework.