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Regarding how long you might want to wait after turning the key to 'Run' but before continuing to 'Start', so that the glow plugs can do their job:
OPERATION
CAUTION: The glow plug system is a 7 volt system.
DO NOT ATTEMPT to test the glow plug system
with a 12V power source or damage will occur.
When the ignition (key) switch is placed in the ON
position, a signal is sent from the sensors to the
ECM relaying current engine coolant temperature
and ambient air temperature (Fig. 21).
After receiving this signal, the ECM will determine
if, when and for how long of a period the glow plugs
should be activated. This is done before, during and
after the engine is started. Whenever the glow plug
module is activated, it will control the 7 volt high
amperage circuit for the operation of the four glow
plugs.
The Glow Plug lamp is tied to this circuit. Lamp
operation is also controlled by the ECM.
With a cold engine, the glow plug module and glow
plugs may be activated for a maximum time of 200
seconds. Refer to the following Glow Plug Control
chart for a temperature/time comparison of the glow
plug relay operation.
In this chart, Pre-Heat and Post-Heat times are
mentioned. Pre-Heat is the amount of time the glow
plug control circuit is activated when the ignition
(key) is switched ON, without the engine running.
Post-Heat is the amount of time the glow plug control
circuit is activated after the engine is operated.
The Glow Plug lamp will not be activated during the
post-heat cycle.