As short a time delta as possible (from the OEMs perspective; the sooner the customer takes it, the sooner we get paid
)
With the degree of solvency of some customers, an aircraft can sit waiting for acceptance for ages, though - months isn't impossible, if they don't have the readies to take the plane.
For airliners the typical time is probably in the small number of weeks; depending on when you count "delivery" for a business jet, it could be months, even years (since the plane may spend many months in a completion centre before the owner ever finally takes delivery)