Quoting Ꭶwan♥Nemö:" just keep the one pack of newborn and go with buying 1's and 2's. babies arent in newborn long to get ... [snip!] ... get a whole lot of them. My son was in newborn maybe a week. Even if yours is in nb longer you can just tighten the ones a bit."
Thats what I did. One pack of nb's then went to ones- just do them up a bit tighter.
I love the walmart brand as well, actually. Cheap, not as bulky as some others, and they don't leak- they even seem to hold in the explosions better than huggies!