My cell phone died the night before leaving for Disney World last month, so Verizon sent a replacement to the resort for me. So not exactly the same as shipping ahead, but I can give you some advice.
First of all, I would not use the postal service. I know that because when I went to the front desk to ask if my package arrived the cast member jokingly said something about how it was not there yet and she hopes it wasn't sent through the postal service (it was shipped by Fedex). I asked why and she said "because you won't get it". She explained how it works but I can't remember. Basically she said use Fedex or UPS. Thankfully when we got back to the room the package was sitting on the bed.
As for the address. Double check the address, but here's how I had Verizon send it.
Disney Art of Animation Resort
1850 Century Drive
Lake Buena Vista, Orlando, FL 32830
Hold for guest (insert name) checking in on (insert check-in date)
Hope this helps!