Answer:
Occurs when the customers receives the rights to receive considerations.
Step-by-step explanation:
For a contract to be valid, it must have some consideration. Consideration may be in the form of cash payout or any other manner as the contract specifies. The contact itself usually determines when payment is due.
Different types of contacts determine when payment is due. For example, there are contacts that wild demand for down-payment before the commencement. Others will specify full implementation before any payments.