98 Civic EX 4-door sedan Automatic D16Y8

I'm having idle speed problems, but I have not yet tried to adjust. The shop manual says adjust idle speed with the IACV connected, and to adjust by means of the air bypass screw. The screw when I checked it was less than 1/2 turn open from the fully closed position. Is that reasonable, or have others found it necessary to open the screw more turns? Or is there no "rule of thumb" at all as to how many turns are typical?

I also found a TSB that says the PCM will "learn" new settings for the IACV after adjustments are made to the screw. Is that true for my specific model?

Thanks any advice!