Web, the water should be at least 1/2 way up the skimmer for correct operation, Hayward faceplates have an arrow at the 1/2 point. I usually prefer to have the water at the 2nd screw down (looking at the skimmer 12 screws secure it 4 across the top, 4 more on the bottom and 4 on each side [ - that's 16 not 12! - the 4 corner screws are pulling 'double duty' being both side and top/ bottom ]) This allows you some evaporation/ backwash leeway, but isn't so high that a good rain will stop the skimmer from skimming (you need at least 1/2" clearance for the skimmer to skim, otherwise you just have a big square suction port on the wall)
Hope this answers your question, if it's a little vague, I or one of the others will further explain what I've tried to say.

If the weather is still favorable, take 1 day each week to just enjoy your new pool and without thinking about the various 'issues' you've had with the installation