There is a shiny Ditto in the egg list with Imposter, Quirky nature and 15/15/15/15/15/15. That might be the one you are given? If so, the IVs are clearly perfect already. :)
Good point regarding the inbreeding check, I think I forgot to disable it.
The Masuda method triggers for traded mons, including from Wonder Trade, giving you a 6/4096 chance of a shiny (8/4096 if combined with Shiny Charm).
Another thing you might wish to know. Since due to how ability inheritance works (you inherit from mother or non-ditto 80% of the time) you would end up with a 1% chance to get a hidden ability from a non-HA (20% to not inherit, then Polished Crystal's 5% HA chance generally). To make it easier to get HAs, a new "breeding item" feature was added -- if one of your parents hold an Ability Capsule, the baby has a 25% chance of getting its Hidden Ability. If both do, this chance is 50%. Aside from that, breeding works pretty similar as in generation VII, here are exact details:
* 3 DVs are inherited from parents at random
* 5 DVs if your parents have a Destiny Knot
* Nature is random unless a parent holds an Everstone, then that one is inherited. If both do, Nature is inherited at random
* EV-enhancing items (Power Weight, etc) gurantees inheriting one of the DVs from that parent. If both parents hold the same one, the DV is inherited at random
* Ability is inherited 80% of the time from the mother or non-Ditto. If a parent holds an Ability Capsule, the baby gets the HA 25% of the time. If both parents do, the baby gets the HA 50% of the time.
* Ball is inherited from the mother or non-Ditto. If both parents are the same species, Ball is inherited at random. Unlike in vanilla gen VII, master balls can be inherited
* Form is inherited the same way as Balls (matters for Magikarp and Arbok, Unown can't breed)
* Egg moves can be inherited from both parents
* Shiny rate is the same as wild (1/4096 or 3/4096 with Shiny Charm) unless the parents are of different OTID in which the Shiny rate is boosted by +5/4096 to 6/4096 or 8/4096 with Shiny Charm