If the carb linkage is set up right...

The engine will start at 0 throttle stick position, and full throttle trim position.
The engine will Idle OK as low as 0 throttle stick and 1/2 throttle trim
The cab will be FULLY closed at 0 stick and 0 trim. (make sure the servo doesn't buzz... if it does... adjust the linkage)

(assumes no digital trims... this is why I don't like digital trims. We NEED the mechanical ratcheting trim on throttle)

When the main stick and the trim are both at full the carb will be WIDE open and the servo won't buzz.

With this setup... unless you want the engine to die in the air, fly with the trim at full, and control the engine with the main stick. When taxiing, you may need to have the trm a little less than full... after you take off... push the trim all the way up. That little bit it prevents the carb from opening from being pulled back won't reduce the take-off power enough to reliably easure with a tachometer... so don't play with throttle trim unless you have altitude to allow you to fumble a bit.