Yup, it's a jigsaw puzzle.
Think of it this way, the sting has to have a clear path to the hole, so what you do it put all the strings on with the harness outside the body, and make sure that each string will have a clear path to it's destination. Imagine you have a huge opening, and you are pulling the whole thing at once and they all have to land in their hole.
Once you have that outdie the body, put the whole harness inside the body in the exact same orinatation. It should lay in the body the same way it was outside, with all the strings having a clear path to their destination. Once you have that, pull each string 1/2 inch or so, so they all move forward together. You are keeping the strings from getting tangled. You should have all the pots poke through at the same time.
Some use plastic tubing instead of string. It fits tight over the knob shaft, but will still go through the hole.
Oh, put some masking tape over your f-hole edges, you will chip the paint with the pots. Ask me how I know....
Looks like you have quite a distance there.. Have fun!
-John