Start the drones a month before starting the queens. Put the drone cell frame in 30 to 40 days BEFORE your first grafting of queen larvae. Feed those drone mother hives with copious amounts of protein, pollen sub. The bees will not produce drones unless they are feeling flush with resources. The queen may lay in the drone frame and larvae starts, but the bees will go back and canibalize most of the drone if they feel the slightest bit resource strain.
What I do is then wait until the drone brood is capped and maturing. When it is about 1 week from emerging I go pull the drone frames out of the hives and consolidate all of the drone brood into one or two queenless colonies, labelled The Barracks. The drones emerge into those hives only. I can then keep tabs on and treat only The Barracks for mite if there are any issues. When the drones sexually mature and start flying, they redistribute themselves amongst the other nearby hives in the apiary, as well as entering and loitering in the mating nucs.
Location of the hives and nucs does not matter. Nature sorts itself out. My drone hives, The Barracks, are setup in the same yard area as the mating yard. Perhaps 1/8 to 1/4 mile between them at most. Never had a concerning problem, having had many many great successes.
It is really as simple as that. Not sure what else can possibly say or offer about this.
Hope that helps.