Stay tuned-- this is a feature we are working hard on!
In the meantime, we recommend adding a single event for each day of a festival that you are playing at in Bandsintown Manager or with our bulk upload tool. Once you figure out which day of the festival you are performing, just delete the events you no longer need.
If you don't want to add each day of a festival, you can also create one single event on the date of the first day of the festival and add an event name such as "Coachella Festival: April 15-17". Just make sure to check the box for "Display instead of venue name" when you are creating or editing the event.