Wars the ideal time to start queuing?.
Start queuing near the flight time and when you see other people queuing. You won't be boarding until 15-20 minutes before the flight if not lather as the aircraft is inbound. No need for this nonsense of paying for priority boarding or reserved seats. Biggest money spin ever and not worth it. Most airports should have two queues one for priority and the normal queues.
IMO Bristol is the worst UK airport for passenger order and boarding aircraft, have yet to fly from there when it hasn't being a complete shambles...