Off the top of my head, I'd say:
Wipes, wipes and more wipes
nappy sacks (Big W has them really cheap)
baby cotton buds
nappies in the next size up
nappy-san
extra laundry detergent
dummies (if you plan to use them)
baby panadol - good to have ready just in case
extra batteries for all those cute toys and gadgets you've gone and bought. Better still get rechargables as you go through so many batteries.

Also stock up on some household basics like toilet paper, coffee/tea, long life milk, biscuits or snacky sort of things for unexpected guests or just for your snacking. You may not feel like going shopping in the early days.

HTH