Payment of both minimum wage and overtime compensation due an employee must ordinarily be made at the regular payday for the workweek, or when the pay period covers more than a single week, at the regular payday for the period in which the particular workweek ends. However, when it is not possible to ascertain, prior to preparing the payroll, the number of overtime hours worked by an employee in the last workweek of the pay period, the requirements of the FLSA will be satisfied if the employer pays the overtime compensation as soon after the regular payday as is practicable. Such a payment should not be delayed for a period longer than is reasonably necessary for the employer to compute and arrange for the payment of the amounts due, but in any event not later than the next payday after such computation can be made.