You're right to be concerned. It has been one of our biggest issues since moving into our new home in Las Ventanas.
DO NOT ASSUME THE POST OFFICE WILL KNOW. Even after the developers contacted them, we continued to have issues. We had a piece of certified mail sent from within Irvine take three weeks to reach us. I had to go pick it up at the Sand Canyon office and when I handed the delivery slip to the postal worker, he looked at it and said "Seedling???" I had to explain that we were a new address. The mail is pretty much OK, now, but we still get some stragglers and surprises. FedEx/UPS seem to be more on top of it.
Also be careful in that many companies use large address databases and they will "autocomplete" or verify the address. So, you'll change something online (bank account, etc.) and then go back to see that it has corrected the address to something else. For example, ours is often changed to "Sterling" or "Sanderling," which are existing streets in Irvine. Phone reps will also often struggle with this and have to get a manager to override it, after questioning several times whether your address is correct. Delivery men will punch you into their GPS and go to the wrong part of town, as they often do the same thing.
It just requires a lot of attention.