I would only do as you are decscribing if the corals in question came from a significantly lower-light environment than your tank. (Not a sure thing! This used to be significantly more common than it is these days.) I would leave them at least a week or two before moving them up.
Just in case...
If you use a light meter (lux or PAR, etc) to source and place your corals – in other words use a light meter to match the light in the new tank to the coral's light in its old tank – there might be no reason at all to do it.
And having said that...
If it's not too late, contact the former owner of your frag and get their measurement so you can just match them in your tank.
(P.S. It's not the ideal way to go, but even if neither of you have a light meter, there's still a better solution than guessing and waiting. Try a lux meter app for your smartphones....ideally you can both use the same app. The only real problem with apps is that some apps don't work with some phones....typical software issue. ;) Take some reference readings – of sunlight, for example; google for other references – to make sure your app is giving you good readings before you take it to your reef. Post here or even PM me if you need help anywhere along the way.)