Traditional practice distinguishes the dark moon — the last invisible days before conjunction — from the new moon, which older usage means the first crescent you can actually see.

Modern astronomy calls the exact conjunction 'new', which is the one moment the Moon cannot be seen at all, and that has quietly overwritten the older sense. Practitioners who keep the distinction give the dark days to rest and endings and the first crescent to beginnings, which is a more sensible division than putting both on the same date.