The FADEC will protect you from most start anomalies and you are pretty much a spectator during a ground start. One of the few exceptions is for a starter valve that has failed open. For that, you have this: Start Valve Fail Open on Ground.
A good rule of thumb for a normal acceleration is that TGT/10 should be greater than N1, if not you will get a depulse (sharp reduction in fuel) as the FADEC attempts to keep the engine start viable.
Everything here is from the references shown below, with a few comments in an alternate color.
If TGT is greater than 120°C the FADEC will motor the engine and inhibit fuel flow until TGT decreases below 120°C.
If a sub-idle stall condition is detected, a rapid increase in TGT may occur with a delayed increase in N2. The FADEC will initiate a fuel depulse, as the TGT approaches 750°C, to prevent an exceedance. During the fuel depulse, the FADEC will command a near zero fuel flow to clear the stall and then progressively command higher fuel flow to re-accelerate and start the engine.
When is the engine confirmed started? You can look up to the fuel panel and see when the alternate fuel pumps are on, that's a good clue. But an even better one is to notice when the red arc on the TGT dial changes scale and becomes smaller.
THE SPEED BRAKE HANDLE MUST BE FULLY SEATED IN THE RETRACT DETENT TO PREVENT INADVERTENT EXTENSION.
Gulfstream GVII-G500 Airplane Flight Manual, Revision 4, August 29, 2019
Gulfstream GVII-G500 Production Aircraft Systems, Revision 3, July 15, 2019
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