Regardless of the time of day you decide to fly, the ticket price will remain around the same. Book flights from Shannon to Venice as you normally would.
Shannon (SNN) is the airport you will fly out of if you book a flight from Shannon to Venice. You should not have trouble finding flights to Venice from Shannon; the airport handles an average of 0 outbound flights to Venice per day. You should also have plenty of airline options to choose from since 1 airline has flights from the Shannon airport to Venice. It is only a 2.1 mi journey to Shannon (SNN) from Shannon’s city center.