Huangshan North to Guilin by fast train

After visiting the Huangshan area we want to go by fast rail from Huangshan North to Guilin. We realise this requires one change in rides. But where is the best place to change? Shangrao? Yichun? Somewhere else? We do not speak any Chinese and are hoping we can change somewhere where it will be easy to find our way to the second trip. How long should we allow between arriving and leaving at the changeover, when we book our tickets?