Start with passport validity and any visa that needs an appointment. Then lock the long-haul flight, then the first night's hotel, then internal travel. Reversing that order is how itineraries unravel.
We sequence the work, flag documents early, and keep one thread for questions so you are not coordinating airlines, hotels and cabs in three different chats.
If several people are travelling, send names and passport details together. Group bookings stay cleaner when the file is complete from day one.