The baseline row is the most important. Small mistakes here will have magnified themselves once I get to the other side of the room. Hence, this was another measure, measure, and measure again stage of the installation. Using the laser level to identify the correct intervals, the cross T's were added. I used a speed square to make certain that each was at right angles before I rivoted the cross T to the wall molding. I have never hung a suspended ceiling so "slow and deliberate" was the name of this game. I think I will pick up on speed once I get into it.