Hi, you can plan for a Meghalaya Vacation during Durga Puja as October is one of the best month to visit Meghalaya. As you are from Kolkata, you can take a direct flight/train to guwahati and from guwahati you can book a cab to shillong ( 2 hours drive). You can cover Shilong, Cherrapunji, Mawlynnong and Dawki in 3 days.