They’ll give you the rest of the pack that was opened for your baby in the hospital. Unless your baby is very big, I think you can buy some NB diapers first. Cheaper too. Heh. Different NB diapers are also of different sizes. For eg. Huggies platinum/Merries NB size is physically bigger than Drypers/Huggies Gold. The former is better if your LO is expected to be a bit bigger, and the latter’s better for babies with skinny thighs to prevent leakage of pee/poo:)
Yes, they will use theirs and give you the extras when you discharge. I bought a few more packs at home too cos there is a need to change often.