I would start with the temperature that @Kiki said is good, then after your eggs hatch, watch how the babies act. This should work equally well for any species of bird where the babies can walk around (chickens, quail, ducks, geese, guineas, turkeys.)
If they huddle together in the warmest...
If 88 is warm enough, then you're good to go. (I would trust @Kiki on that)
If you need it even warmer, you would need to lower the lamp further (open the top), or else use a bigger bulb (more watts, more heat).
One interesting effect with heat lamps: the lower you put it, the warmer the...