Jacob was 8lb 6oz at birth and we put him straight into 000. They were definitely too big for him, and he could have gone into 0000, but we didn't buy any since we were told he would be around 9lbs! In hindsight, I'm not fussed that the clothes were a bit too big for him as if we'd have bought 0000 he would have been growing out of them within a matter of just a couple of weeks anyway.