My daughter weighed 10lb 7oz when she was born and newborn vests and sleepsuits fitted her for at least a month. We did buy more 0-3 though. What we did before she got here was buy a tonne of sleepsuits and vests in newborn and 0-3 (when people buy you gifts, they normally buy outfits) as they tend to spend most of their time in sleepsuits to begin with. If you work on the idea that you go through at LEAST two sets of clothes a day, then 14 sleepsuits and 14 vests will last you a week, and you can then rewash. They're so cheap in most places though you'll end up with more, but I'd say 14 vests and 14 sleepsuits in each size is enough, plus any little outfits for visiting etc. Plus depending on the time of year the baby is born, you'll want a mixture of sleeveless, short sleeved and long sleeved vests xx