Big Guy has it, as per the RFM.
It's a good idea (indeed, see RFM para 2-5) to check the throttle for full and free BEFORE the start, to note the 'engine' legend position of the throttle at the idle stop and then to open it to just below the idle stop at 12% or above, and with indications of engine oil pressure. (212 is the same, but rotors will also normally start to move before the throttle.) That way if you do get a voltage drop or have to close the throttle in a hurry, it's easy. Remember too, that on both the 212 and 412, if you are holding the throttle back against the idle stop, friction may result in the plunger not retracting when you operate the idle stop (solenoid) release. (As Note in RFM.)
Incidentally, I would advocate the same procedure for the AS350 with collective throttle and for the EC120.
As for 412 angle of climb, see the Class 1/Perf A segment at 45 KIAS, as someone else has pointed out.
Now I'm exhausted....all this 'idle stop' chat. (And no, the soubriquet has nothing to do with 212/412!)
Idle Stop.