You can't attach the strings to the "headstock tuners" till you have the "bridge in", that's why it's critical to make sure the bridge is in the correct position firstly. Tape over the body so to be able to make your measurements and pencil mark without marking the body. As said, go to the how to section and have a good look at the video's Utube also have plenty of "how to's" to check on. Good luck.