In your situation, I would. Not for as long as you would Un-cured rock. But Maybe a week or two. I say this because, you're already going to have a mini-cycle from stirring up your sand that's currently in your tank.

So, adding more LR in there will only increase the severity of it, IF there is any un-decayed or still decaying organisims on it... IE: die-off from shipping. Giving this new rock a week or two in a QT with good flow and large water changes will assure to help keep those dead organisms out of your tank. Which, in turn, reduces the chance of another mini-cycle from happening, or at least, reduces the severity of the mini-cycle.

Hope that made sence.