I'd definitely skip newborn. Callum did fit into xsmall Sandy's, but only for about a week and I had to boost them from birth. The xsmall OWW I got for him was way, way too small from birth. He fit well into smalls - Dunk N Fluff mainly and stuff I made using the Darling Diapers (same as DnF) pattern. And also fit well in the BTP nappies I had. In fact, there's a photo of him at about four days old wearing an Itti Bitti - it's a medium and it's not on the tightest poppers.
ETA: Even Iris (8lb 15oz) fit well into our BTP nappies at birth and went straight into smalls, not newborn.