I only bought a blueberry OSFM at the expo so Ari was not exactly a newborn. When I first tried it he was 9 weeks old and about 6kgs.
I like the fit on him, because its a OSFM the backside gives good coverage
. I am not sure I would put it on a newbie straight away with the specific insert as it would be quiet wide through the crotch but I assume with less stuffing it would scrunch up a bit and be fine.
I think I put a photo of him wearing it in the fluffy mail section. He now wears it in the 2nd rise setting.