It's covered in the second drsfostersmith.com
link (click on it)
"If you employ metal halide lights, place some sort of screening material above your coral during the first few weeks of acclimation. The screen could be egg crate light paneling or fiberglass mesh. Also, reduce the photoperiod by half for the first week and gradually add an hour each week to reduce the risk of light shock. A good indication your coral has adjusted is when it appears fully expanded and displays full coloration."
The first link goes into a TON of more detail for each type of coral but following the above advice works for the majority of corals.