We have a poll on this subject, click here: What size was your baby wearing at birth?

Aidyn had a couple of 0000 outfits, but he outgrew them pretty much in the first 2 weeks!
Although you will find size differences depending on the brand of clothing too - ie, Bonds = smaller fit, Pumkin Patch = larger fit.

HTH
Thank you to everyone (and Ambah for posting the poll link). For helpful indeed!