If u don't want to hang a plumb Bob in center of every light. Just draw a layout of the room with the tables and just measure from the walls to first table legs from each wall. And write it on ur layout paper. Measure from table to table. Etc. And after carpet is down. Go along and pull ur measurements and put painters tape on the new carpet where all ur table legs go. And when u start putting tables back u can just put them rite where the tape is put down at. Hope that helps.