My old girl was 5 pound 2 and 47cm long, the bonds 00000 suits were huge on her but my second daughter was 7 pound 4 and 48.5cm and she barely fit into the 0000 bonds suits. DD2 was only a kilo bigger and a cm longer then DD1 but it was enough to make her jump a size. But both of them fit into other brands 0000 easily for several weeks. Alot of the smaller sizes i had got passed to my sister and then back again so even if bub doesnt wear them much they can always be passed along to someone you know.