Dixie - for pre-turbo temps, I have always been told to let it idle until you see <300* on the EGT gauge. Driving down the highway at 70 MPH on flat ground, I usually see in the area of 550 - 700*, depending on traffic (constant speeding up/slowing down) and possible head/tail winds. Climbing a grade you can see anything, depending on such factors as are you towing and/or hauling anything, outside ambiant air temp, head wind, how long & steep is the grade... .....
But as long as you don't pass 1250* and keep it past there for more than a few seconds, you are fine.
Tom