I've been doing some similar planning with an October baby due and from what I've been hearing the Bonds Wondersuits in size 000 are great for NB as they are sort of fit a bit small, sort of in between sizes 000 and 0000. I'll probably get four or so of those and then maybe another three suits in another brand in 0000 (will look for these second hand at the Bubs market as I'd imagine most will only have very light wear in this size).

Good luck...