what is the purpose of the switch? Are you adding a second pickup and wish to have options (neck pup/neck & bridge/bridge) or is it just for on/off for the whole harness? If this is true, look at the wiring group for specific diagrams for the harness design to see where switch is added.
If the latter, and you wish to change from acoustic to electric, just use the volume control for that.
I would put it between the harness and the jack.
I('d wire in some lights or something and use the switch for that!