Factories run to a production schedule allocated weeks or months in advance. An order does not enter production the moment it is placed; it is allocated to a slot in the existing schedule.
Standard-range product typically holds shorter allocation windows because it fits alongside existing runs. Custom colour, dimension or specification requires a dedicated production slot, which is scheduled against the factory's committed capacity.
The practical implication is that lead time is set at order release, not at enquiry. The window is confirmed against the schedule the factory is actually running, not against a generic quotation. A disciplined supply reports the allocated production date at acknowledgement so the programme can be planned against a confirmed window.