I second on the wondersuits, either buy a size bigger or buy the target or kmart brand ones.
When it comes to wondersuits bigger is better anyway so you can use the mittens.
Don't forget even though you are really close to delivering your bub could be a completely diff size to what your being told.

DS was 7lb 14 and 0000 were a nice size for the first 2 weeks and 000's just gave that little extra room.

One thing I found though is my family has long backs and short legs so does dh's family, so of course we ended up with a bub that has a long back and short legs. this means his pant size is always smaller than his top and while his legs will fit into 000's his top is 00 and his socks are for that of a 6 month old 'cause he has huge feet so there is no way know he will fit into a 000 suit anymore. lots of bagy 00's for us here.