If yes, how does it work?
If not what are you using?
The BG 3.0s we have (almost exactly the same as the 4.0s) didn't fit her until she was about 1.5 - 2 months old. And even then, they were quite a bit bulkier than her other diapers, like her small BG AIOs, so I wouldn't necessarily grab for them first.
That being said, I LOVE our one-size BGs - I just don't think they will fit a newborn. As far as OS diapers we have FB, BG 3.0s, BG organics, RaR, Swaddlebees, Blueberry and the ONLY one I could see fitting a newborn is the Rumparooz (though I didn't try them on her right away).
Hope that helps!
BG 3.0s did not fit #2 until he was 2 months old.
We used prefold & kissaluvs fitteds with thirsties covers until they fit.
I have a blog post here about cloth diapering a newborn.