What will be the date of payment to ascertain the time of supply of goods

In terms of the Explanation 2 appended to Section 12, the date of payment shall be the earliest of the following dates:
(a) Date on which payment is entered in books of accounts of the supplier; or
(b) Date on which payment is credited to the bank account.

(ICAI FAQ PUBLICATION 06-09-2017 TIME FOR SUPPLY OF GOODS: FAQ NO. 4)