“At the end of the day it seems that there is nothing wrong with it……”
Our Rav told us that if it will be easier for you or you will lose money, then it is perfectly muttar to buy things beforehand but you should be careful to put it away and not tell people about what you bought. This is because if there is someone who ch”v doesnt have children that sees you preparing for your baby before you have it, it could be an ayin hara.
So you can do what you have to do but dont flaunt it