ClearUserLog();
//Log Time Started
UserLog("Set TimeZone Started at" + gs.nowDateTime());

//Query Table
var gr = new GlideRecord('sys_user');
gr.addNotNullQuery('location');
gr.addNullQuery('time_zone');
gr.query();

//Update Records
while (gr.next()) {
    gr.time_zone = gr.location.time_zone;
    gr.setWorkflow(false);
    gr.update();
}

//Log Time Ended
UserLog("Set TimeZone Ended at" + gs.nowDateTime());