At what point should the 850 HP lever be moved into that position?

Obviously for cruise, but should it be before that on the climb out or at a certain altitude?

I do a lot of shorter flights of 100 N.M. so my maximum altitude is only up to 10,000 ft for those.

I use it mainly for climb..

I was thinking of using it at some point during the climb but maybe not on early climb out.

The way I understand it is that the Inertial Separator should be on for Taxi and Take-off and continue to stay on if there are icing conditions. During this time you would not want the lever in the 850 position until after the Inertial Separator has been turned off. At some point the lever should be moved up to the 850 hp position, I'm just not sure exactly when. Steveokinevo may have covered it in one of his videos, but I don't remember which one.     

From memory I think I read in a couple of reviews of the real aircraft they would engage once established in the climb. This is what I do then disengage on descent (if I remember!) which can be a trap if you forget. Have made a few flapless landing in my time 

Hi, Ross.  I believe you are correct.  At least that is what my TBM 850 checklist says--engage on the climb, disengage on descent.

Thanks guys.

I did an IFR flight today with a distance of 200 nm. As such my cruise altitude would be about FL200. I had clouds and cold/icing type conditions through 15,000' so I didn't shut off the inertial separator and move the 850 lever up until after I broke through the top of the clouds. I know icing conditions are not simulated but I still like to fly as if it did.