Hi Paul, You need to experiment! Can I suggest that you aim to start off at around 60C and gradually raise it to perhaps 65 to 68C over the first day or however long you are conching at. As usual there probably isn't a "right" and "wrong" - it is what works in your conditions with your beans. Too high and you may negatively affect the flavour and too low and you may not drive off the bitterness.
Duffy