Honestly if just buy packs because my son is almost one month and the new born ones fit fine but his poops pops out the size. And I prefer the size ones on him. I was just given s box of new born diapers and of course I didn't want to put them to waste but definitely sticking to size ones after the box is empty. Even the hospital had him in size 1 at the hospital
I have big babys so i usually only buy a small pack or 2