The orbiter Endeavour's Flight Readiness Firing on April 6, 1992. Video source: 3210andLiftoff YouTube channel.
The last time Launch Pad 39A's flame trench filled with fury was July 8, 2011, the final launch of the orbiter Atlantis and the Space Shuttle program.
That hibernation is scheduled to end on February 11, 2017, when SpaceX is to perform a static test fire of a Falcon 9 first stage on the renovated pad.
The Shuttle program's version of a static test fire was called a Flight Readiness Firing, or FRF. Each orbiter had one before its first operational mission.
The last orbiter FRF was April 6, 1992, on Pad 39B. The orbiter Endeavour lit its three main engines for 22 seconds. The Shuttle went nowhere, because the two solid rocket boosters were not lit and remained bolted to the mobile launch platform.
A Falcon 9 first stage on Pad 39A today. Image source: SpaceX Instagram.
The Falcon 9 scheduled to launch a cargo Dragon to the International Space Station on February 18 rolled out earlier today from the nearby horizontal hangar. For the first time in Pad 39A's history, a rocket rolled horizontally to the pad and tilted upright. Ever since 1967, all NASA missions rolled out vertically atop a mobile launch platform carried by a crawler transporter. SpaceX uses a transporter erector, also known as a “strongback.”
In the above image, the Dragon and upper stage are not atop the first stage. SpaceX lost its customer's satellite on September 1, 2016, when it conducted a static test fire at Pad 40 with the payload above. A helium bottle failed, causing an explosion and the destruction of the satellite. SpaceX no longer conducts static test fires with the customer's payload installed.
According to one report, SpaceX will conducts its test fire tomorrow sometime between 10:00 AM - 6:00 PM EST.