Hi, Kerry!
Disney's Magical Express makes our arrival and departure days so easy! Not only can we get a ride to our Walt Disney World Resort hotel, they also take care of our luggage with little more than a wave of their wand and a "Bibbidi Bobbidi Boo!" Well, it does take a little more than that, but they sure do make it look easy!
The yellow luggage tags you mentioned give a heads up to Orlando International Airport (MCO) that you are headed to a Walt Disney World Resort hotel. They will continue looking for these lovely little tags right up until 10:00 p.m. So, your planned 8:30 p.m. arrival is definitely fine for using the tags. Your bags will arrive on your guest room doorstep within a few hours.
There are a few things I want to mention to you so you can make a better decision on how to handle your luggage. In my experience, it usually takes three to four hours to receive our luggage. If you arrive at 8:30 p.m., then that would put your luggage getting to you around midnight. That is a bit late, so you may want to pick up your luggage yourself at baggage claim and carry it to Disney's Magical Express motorcoach. The driver will help you stow your luggage under the bus for the trip to your resort. When I have late airline arrivals, I have started doing exactly this, so that I could have my belongings to get ready for bed and not be worried about listening for the knock at the door signaling my luggage's arrival! During one late arrival night, Bell Services actually held our luggage for us until morning. While that was so considerate of them, I could not sleep all night waiting for that knock and then worrying if our bags had been lost by the airline! So, my advice to you is to consider forgoing those handy yellow tags.
I hope this information helps you plan a magical first day at Walt Disney World Resort, Kerry!
Brandy