In Indiana, the first day that banners and signs related to a nationally recognized sporting event to be held in Indiana can be displayed is 21 days prior to the event.  (IC 7.1-5-2-7 & Rule 1-38-1)
This year for the May races at the Indianapolis Motor Speedway,  that date is April 23, 2016, which is 21 days prior to the Grand Prix of Indianapolis to be held on May 14, 2016.
The banners will need to be removed five days after the close of the Indianapolis 500 on June 3, 2016.
For more information, contact any member of the Hospitality Group of Bose McKinney & Evans LLP.