Here's a way to check if you've got the nut-height correct, first of al get yourself a 30cm/300mm Steel Ruler as used by metal workers for marking out sheet metal, you can buy these from your local Bunnings shop, next place the Steel Ruler on the neck so that the edge of it is touching the frets, and it is standing perpendicular to the frets, then slide it up the neck so that the end of the Steel Ruler (where the zero mark is) just touches the front edge of the nut and the Ruler is sitting on the first few frets after the nut, you'll know when you have the nut height correct when the bottom of each string-slot lines up with the edge of the Steel Ruler, using this method, I have been able to get the nut heights on all my guitars so that the action at the first-fret is nice and comfortably low, but buzz-free.