When starting the T-6A, the PCL should be:

During the start procedure of the T-6A, the Power Control Lever (PCL) should be pushed forward until the green ST READY annunciator is illuminated. This step is crucial because the ST READY light indicates that the engine is ready for operation, ensuring that the necessary systems have achieved the appropriate readiness state for a safe start.

Once the PCL is moved forward, the pilot monitors the engine parameters, and the illumination of the ST READY light confirms that the engine systems have stabilized and are ready for the next stages of operation. This step is part of the standard operating procedure that enhances the safety and reliability of the aircraft's startup process.

Other options do not align with proper procedures for starting the T-6A. Pushing back the PCL until a red warning light appears can lead to miscommunications and confusion regarding the engine's status. Keeping the PCL in neutral until the engine is stabilized is not the correct action as it delays initiation of the start sequence. Lastly, pushing the PCL to the maximum setting immediately can overwhelm the system and is not advised during the start procedure, potentially causing engine issues.