So I've been playing around with the breeding and (pardon me if I'm late to the party), but it appears that the eggs IVs might be created when the egg is spawned, NOT when you pick it up from the Day-Care man.
I saved before receiving each egg to see if I could change the IVs for each egg of the same nature/ability, just like in 4/5th gen. However, each time I visit the judge, I get the same response and potential from the Pokemon. This is making me believe that the IVs are created when the Egg is, not on a per frame basis. I've tried things like encountering wild Pokemon (both Hoards and singles) and even Wonder Trading before picking up the egg, but nothing has changed the outcome of the Judge.
Has anyone come up with a way to change the IVs? Or is mass breeding my best bet still? Cheers and let's crack this sucker wide open.