Gabby's weight prediction was 8lbs 13oz. She was born 8lbs on the nose and lost a little while is hospital. She was in 0000 for probably the first month. She had 2 00000 outfits that she fit into but could only wear them for the first couple of weeks.
I would say to have some 0000 outfits unless you know for sure you are having a bigger baby (say, if the prediction is 9lbs or over). Like Shannon said, the wondersuits tend to be smaller than other clothes so you could probably get away with 000's in those. Gabby is in 000 at the moment but 00 wondersuits fit her perfectly.

Nadia - LOL @ the foot size comment!