Breeding a Pokémon with 6 IVs is never easy. The Ditto 5 are only good for getting started, since they only have one guaranteed IV each. You can use them to pass down natures, but other than that, I would recommend using breedjects or Pokémon from SOS chains (length of 30+) instead, since they should have more perfect IVs.
After that, you’re going to want to have one parent (with your desired nature) hold an Everstone and the other hold a Destiny Knot, and you’ll need to remember how many perfect IVs they have before depositing them in the day-care. Then whenever you hatch a Pokémon with better IVs than the parent of its corresponding gender, replace that parent with the new Pokémon (remember to give it the item). Also note that by “better IVs” I’m only referring to perfect IVs; if the parent has 17 IVs in a stat and the child has 23 IVs in that stat, don’t bother replacing the parent since only perfect stats matter in the end.
Keep in mind that it’s going to take a while even with all this. The Destiny Knot only passes down 5 IVs, so even if you’re breeding with two 6 IV parents (which you probably aren’t) you would still only have a 1/32 chance of getting another 6 IV.