What’s your 912iS idle rpm set to?

When I set my Idle, I warmed up the engine and adjusted the screw with the engine running. (Tie the Tail!).
After that, If I decided it needed a small change, A quarter (1/4) turn between flights is plenty to see a change.
If I had to put a number on it, I would say that One Full Turn will yield a 400-600 rpm change.
A little goes a long way. You will not be giving it "Turns".
Keep in mind that high Idle speeds mean longer landing float distances.

I idle and taxi with the throttle at the idle stop.
Taxiing to the departure end with a tall wind and 2200 rpm would either overheat the brakes or the nose wheel would be lifting off at 30-40 knots.
When I start taxing, I release the brakes and give it a short burst to about 2500 rpm to get it moving, but that will be the last throttle change before the runup area.

Thanks, Bill! Good knowledge. Do you have a photo of the idle screw by any chance/where I can find it on the engine? With what Roger and Rotax Wizard were saying about the screw being loctite'd, did you ever use a torch to heat up the screw before turning it, or did simply warming up the engine and adjusting it with the engine running make that screw warm enough to easily turn? 

Clever idea about attaching a tail tie down to get out and do it on your own. I hadn't thought of that and would have assumed I needed another person. But does having your head that close to the spinning prop while you adjust the screw not bother you?

Is this where the idle screw is? 

OK simply look at your throttle body at the bowden cable lever.  If you have a single adjustment screw this will have Loctite.  If you have a newer engine there may be 2.  Use the outer one to adjust and do not touch the inner.  The inner is adjusted by the throttle body producer to set it with matching the TPS on the other side of the shaft. The inner one has Loctite. 

i did attach a picture last time, but here is is again if you missed.  This is from a 915 engine and shows the 2 screw version.  

Cheers

As others have shown, The adjustment screw is on the Rear side of the Throttle Body (TB).
The Air filter is attached to the throttle body so it should be obvious where it is located.
As shown on the 915 TB, the screw has a spring under it just like on your lawn mower.
Mine only had some witness paint on it.  No Heat Needed,

The idle screw is about 2 feet behind the propeller.  Use caution!
Approach from the rear along the fuselage. Not from the side. (Assuming a High Wing)
A low wing requires a little more planning.
Make a practice approach with the Engine OFF to avoid any surprises.
Keep the screwdriver in your Right Hand and keep your Left Hand firmly on the plane to avoid tripping.
The door or window frame is usually a good place to grip.
There is no reason that ANY part of your body needs to be closer to the prop than the rear of the engine. (3 ft.?)
Always move slowly and deliberately.
When changing sides, Always walk around the Tail.  Respect the Prop!

Tie the plane's tail to a tree or a car. A Tow hitch is ideal.
Use a rope rated for at least 1000 lbs.
2 loops, 4 strands of 3/8" rope should be enough.
With the cowling already OFF, start it up, Warm it up. Then set it to idle.
Turn the idle screw 1/4 turn at a time. CW = Faster, CCW = Slower.
When reducing the speed, the idle may not change until you cycle the throttle once.
Rev it up slightly and then pull it back.
Repeat as needed.
Obviously, this is easier to do with two people, but either way, you MUST tie the plane!  Respect the Prop!