Hi - beginning sourdough baker - though quite a bit of commercial yeast experience

If I am trying to listen and observe my starter, for when to feed, do I feed it when it has doubled and seems fresh and alive?  Or wait until sometime later, when it apparently will fall and/or get hooch on top?  My question is regarding regular feeding, either to keep it going, or to rebuild it to then use it to inoculate leaven.

Thanks for any information.