Folic acid, and reading books added. If it's a boy we should have lots of hand me downs. I have priced cribs and all that, apparently they go through a lot of diapers too ehh
This is only so-so accurate, our baby pooped a billion times a day until she was about four months old, but it's a good rule of thumb:
How Many Diapers a Baby Uses by Age | Babble Soft Blog
You can't stock up on diapers too much ahead of time (assuming you use disposables), because different sizes are needed at different times, and you won't know ahead of time how fast of a growth cycle your baby will be on.