I've only bothered with 24 nappies from birth, which suited both Callum and Iris fine, washing every other day. They grow so quickly that newborn size just isn't worth it, IMHO. I bulked out Callum's stash with some one-size Piddle Poddles, Bububebe and Baby Beehinds. They might be bulky on a smaller baby, but I found the containment fine. And given he was a summer baby, getting clothes to fit over the top wasn't an issue - he only wore a nappy and vest much of the time. The advantage of OS, obviously, is he's still in them now, so not as wasteful cost-wise.