My baby girl is 6.4lbs. when she is born. I bought 2 packs NB only, cause many friends would like to gave us diapers. From the date my daughter is born to now, we used 5 packs NB la! I think 6 packs are enough. I will then change to S when she is 1 mo. old.
My BB was 6.3lb when when was born.
She used 4 packs fo nb, she changed to s size just because all my friends bought me s size, or else she can keep on using nb size for a while.