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 Zurich Kloten - Bologna Guglielmo Marconi: Germanwings (4U).
There is no direct flight on the route from Zurich Kloten to Bologna Guglielmo Marconi
Il volo con scalo più breve dura 7h 15min.