6) Below are the events related to ABC Company: May 1: A customer of ABC Company inquired about the availability and price of a service. May 5: ABC agreed to its customer's terms and conditions regarding consultancy services to be provided in the future. May 28: ABC performed consultancy services to its customer and prepared the invoice. June 7: The customer made a cash payment for the invoice issued on May 28. Assuming ABC Company uses accrual basis accounting, when should it recognize revenue? Discuss briefly. (15 pts.)