Lead Time is defined as:

Lead Time is commonly understood as the time between the initiation of a customer order and the delivery of the product to the customer. This definition emphasizes the importance of tracking how long it takes for a customer's request to be fulfilled in terms of meeting their needs and expectations. Effective management of lead time is crucial because it directly impacts customer satisfaction and can influence a company’s competitiveness in the market.

Focusing on this definition, lead time encompasses all the steps involved from receiving the order, processing it, and finally delivering the product. This perspective is essential in Lean IT because it highlights waste reduction opportunities where a process can be streamlined to minimize delays and enhance value delivery.

Other options do not capture the holistic view of lead time as it relates to customer interaction. For instance, mentioning only the process duration, shipping time, or production period fails to account for the full cycle of order fulfillment, which is essential to properly understand and manage customer expectations in a Lean framework.