I only bought 000 outfits but once my little man was born (weighing in at 3kgs), my Mum ducked off to the shop that day and stocked up on 00000 & 0000's. He was in the 00000's for a month, then spent about a month in the 0000's. Then he grew so much that he barely had any wear out of the 000 stuff.... and has been in 00 for a while now. His bum is a 0 because he wears cloth nappies.