i think that for the newborn stage (really the first 6 weeks) you should be fine with 0000s. some bubs are born bigger and some smaller. the target 0000 that i bought were pretty smack on for age IMO. whereas bonds i find fits smaller ITMS.

any of the clothes bought from the coles aisle section fit bigger IMO. so leila wore 0000 for the first 6 months in that range.

My DD started out in 00000 (5x) as she was 2.7kgs when born (bit of a surprise!). so you never really know if you have the perfect size (i had only bought 000 and 0000 sizes which were swimming on her). she wore the first size for about 8 weeks. then moved up to the next (just to get an idea of timing).

stick with the 0000 and if some seem smaller then you'll probably just end up using them first!

also recommend 000 as some bubs go into these straightaway!

HTH