Asking questions is how we all learned in the first place.

In an earlier part of my life I was an instructor on technical equipment for new entrants in my profession and the ones I found constantly making a mess of things were the ones who never asked questions
With a Heads run I've found the size of the Heads cut depends on the strength of the liquid in the still and what type of low wines it came from, i.e. Low Tech wash like Lentils, Turbo or Grain. You really can't make any cuts by measure, it has to be smell and taste.
Remember, when tasting for cuts, dilute your tasting sample with an equal amount of warm water on a spoon; (
I use an eye dropper for this - very effective) if the sample smells OK then put it in your mouth and let it roll around your tongue then spit it all out and rinse, gargle and spit twice.
A Heads run is done with the accumulated Heads from a number of Spirit Runs. On each Spirit Run you discard Foreshots so there won't or shouldn't be any Foreshots in a Heads run and not much in the way of Tails either
I chuck the Heads from a Heads run down the drain. There's nothing to say you can't use them again I just don't bother.