Nettie I don't know if you'll need 00000...how about a couple of 0000's and some 000. You can afford to have more 000's, since if your bub is small, they'll grow into them. I brought two Bonds 0000 wondersuits and two Target 0000 suits, the Bonds ones didn't fit (too small) and the Target ones did for maybe a week or two?
Riv was bigger though, 9.4lb (4.2kg).

How about, with any 0000's you get, only take the tags off one? Or you could just resell or gift them to those with smaller bubs.