I'm actually always curious to see what you Aussie folks do with your carpets. I consider you guys the experts as carpets are YOUR species and you guys have some of the most beautiful snakes in the world in my opinion. I also think you respect and treat them well.
I do believe that the carpets can be fed a bit more than what we here in the US would feed our boa constrictors. BCI boas are pretty rugged, but certain BCC boas are notorious for regurgitation syndrome when given large prey.
My coastal carpet mix is about 1.5 years old and a bit over 4 feet long which is about 1.2 meters. I have jumped her up to medium rats. She has all she can handle to get it down, but I don't feed her again until I'm fairly certain she's ready.
I actually rub the rat on a quail to get her interested. I'm considering switching between rats and quail as I think she'll enjoy avian prey more than rats. I have a good bit of variety mixed into my boa's diet.
trdt58, I think you should experiment a bit and find your niche. Variety will be a plus, and with my royal and boa I try to mimic nature now and then. I'll feed large prey and then give a longer break then I'll follow up with smaller prey a bit more frequently.
Though with a yearling I'd provide a more steady diet until you have a developed animal. If it takes smalls, go for it and then see how mediums go.
Best of luck raising your snake!