yeah, I got the free egg awhile back and hatched it. I had heard there was this trick you could do with synchronize and SOS where a synchronizer would make the SOS pokemon the nature of the first pokemon in your party, not its own, so I evolved it into an umbreon, but either that was incorrect or I was very unlucky with that 50% chance. with natures, you can either use a synchronize pokemon like kadabra or just breed one you caught until you get it, which shouldn't take too long. If it's a pokemon that can be SOS chained (some can't), you can also take care of IVs by chaining a few to start with, as once you get a chain of 40+ going you're highly likely if not guaranteed to get 4 perfect IVs. It's a bit of a pain and time consuming, but until more people start developing breeding stock it might be your best bet.
By the way, if you weren't already aware, the best breeding road in Sun/Moon isn't a road at all but that little enclosure just south of the daycare. Hop on tauros, press b to charge, and just rotate the control stick around and it counts as if you were moving a lot, all while being conveniently placed so you can see whenever the daycare lady has an egg for you by folding her arms. It's also really nice that they allow you to send eggs to a box or replace it with one of your party members when your party is full, so if you aren't needing to stop to check ivs alot you don't need to interrupt the hatching process to go boot up a pc and deposit.
Ok, I really need to be getting a paper written now so I won't be hanging around, but I'll let you know next time I'm online and I can trade you the destiny knot.