If you're talking about bands who've hit the ball out of the park on their first try, Sydney's MANSIONAIR is a pretty good example. Their debut single "Hold Me Down" took the world by storm early this year, accumulating millions (literally) of streams and views online, as well as a whole lot of buzz.
Rather than rush out with new music, the guys have taken their time, only recently playing their first shows and dropping a new track "Second Night" a few days back. The B-side single is a perfect follow-up for the guys; Jack Froggatt's soulful vocals are supported by some of the most supremely polished production going around.
Having seen their debut live show, I am of the opinion that MANSIONAIR is the real deal. Expect to hear a lot more from them over the coming year -- big things await.