2nd slot is reliable.
check to make sure all slack is out of throttle cable-housing, but don't overdo. do this with the fitting on top of carb, then lock it. check throttle travel...can you "hear" the slide hit top & bottom?
holding the throttle open, screw the idle screw in then back out 2 turns (for now)
fuel filling the line and filter? you DO have an inline, right?
check plug gap?
btw-have we covered the intake connections? gasket & carb-to-intake?