Hi Ankit, The trek from Bir to Billing is at least 4-5 hours. It is suggested that you start the trek early morning so that you can reach Billing in time for paragliding. However, please note that paragliding is currently not available because of monsoons.
Trek from bir to biling is 13 km. If u want to enjoy paragliding it is suggested to book one from bir so that the organizer takes u to biling in his own taxi. This way ur precious time and energy could be saved.