Its better to book now, more you wait much expensive ticket will be. the best (in my opinion ) for that period will be NY to Delhi and Delhi to KTM. If you book as a package it will be expensive what i suggeat is buy two tickets separately. you can buy online. from NY to Delhi you will have e tickets (print out yourself) and from Delhi to KTM it is paper tickets which will be deliverd to you by mail. check cheaptickets.nl, the website is also in english. I used that website to buy the tickets for my trip last july and was quiet satisfied. I am not related to the company in any form.