Turning Point
When having nose up you will have little visual clues to estimate airspeed. So you need to rely on IAS.
When using torque/pedal turn, you do not want to do this too early nor too late as crab points out.
One caution : especially if descelerating towards 20-30 knts, IAS will be lagging, so (probably depending on hardware), you will need to start a little earlier.
As pointed out before, start with lesson one first (ie using lateral cyclic/roll) because you can have higher speed, giving greater margins, before using pedals or torque.
One other advise : do not make 180 at first, but something less say 160-170, this will avoid flying through your own downwash.
d3