If you fasten the snap so that one finger goes into your back, it will feel tight and leave marks when you sit down, and if you adjust it to your stomach when you sit, it will become loose when you stand up.

A baby's body is soft and there is a difference between sitting and standing.

Your baby won't be able to move that much from the time he's a newborn until he can roll over, so even if multiple fingers get stuck in the baby's mouth, it's okay as long as it doesn't leak.

Reference: Video on how to apply cloth diapers