There is no timestamp for the aerial footage (unless you ask WTAE who took these shots). But I can tell you it is from the evening of the shooting and since there are no shadows anymore it was probably around 9pm (sunset was at 20:51).
Another piece of info that supports my assumption: The police car (blue) is M500-010482 and at the same spot where it was parked by BWC2-122110 when he arrived the scene just before the shooting started. Also the motorbike is still in place.
By the way: They really left the dead body there overnight. Here from a Butler Eagle article:
"Butler County Coroner William F. Young III was unable to attend the campaign rally for former President Donald Trump on Saturday, July 13, because of other engagements, but he found himself at the Butler Farm Show grounds after midnight Sunday to examine the victim who was shot at the rally.
Young and a deputy coroner confirmed the death of Buffalo Township’s Corey Comperatore early Sunday morning and sent his body to the Allegheny County Medical Examiner to complete the autopsy.
The coroner and another deputy later returned after 6 a.m. to the American Glass Research (AGR) International building, where he climbed onto its roof to confirm the death of Thomas Matthew Crooks"