My kids were pretty big 4.3 and 4.4kgs ( I knew they were going to be big)they just went straight into 00 apart from a couple of 000 i was given as presents but they only lasted about a week or so and i think it is a stupid waste of money buying expensive clothes for babies to just lay around in Really they never get noticed because they are alway wraped up. As for singlets i just used 0 from the start they are a little long but they are very tight to start with and stretch up with the baby. hope this helps someones bottom line?