It depends on your altitude, gasoline used and the camshaft
I would start with between 1/3 to 1/2 turn out from gently bottomed out, set the center carb idle mixture screws 1 1/2 turns out from gently bottom in all the way
The end carb closet to the fire wall is the worst one to set properly, take your time and reset the center carb up last after your happy with idle speed and mixture adjustments with the other two