The CGST Act, 2017 does not provide separate provisions for ascertaining time of supply of goods through/by e-commerce entities. Accordingly, the same provisions as to time of supply of goods discussed above will be applicable whether a supplier makes supply through e-commerce entity or the e-commerce entity himself makes the supply.
(ICAI FAQ PUBLICATION 06-09-2017 TIME FOR SUPPLY OF GOODS: FAQ NO. 12)