Noni, I'm buying some stuff in 0000, and some in 000. It really depends on your bub I think, and what you prefer. Some of my friends refuse to buy anything in 0000, but their bubs swim in 000 for the first month! I don't want to do that, so I've got some tiny stuff in case our bub is small (which I'm sort of assuming it will be!).

Different brands size differently too, just like adult clothes