We do not have enough data on this route to provide a reliable graph showing how many days before departure it is the best to book.
However, usually the closer it is to the departure, the more expensive the tickets are.
The most popular airlines on the route Budapest - Nagyszeben: Austrian (OS).
The cheapest flights you can book on the route Liszt Ferenc (BUD) - Sibiu International Airport (SBZ).
There is no direct flight on the route Budapestről Nagyszebenre
The shortest flights with change last about 7h 25min.