Greetings Estrella and welcome to planDisney!
I have been in your shoes many times! My family has made a reservation at a
Walt Disney World resorts collection hotel and added a day to the trip because it was cheaper to fly in a day earlier! We then had to find a hotel to stay for that one night and then transfer our luggage to our Disney resort for the main part of our trip.
Estrella, since you are staying at an off-site hotel for that first night, you will need to take your luggage with you on your check out day and take it to your Disney deluxe resort on your own. My suggestion is to arrange for a ride share that will accommodate your family and your luggage and head to your Disney deluxe resort the morning you can check-in. You will be able to drop your bags off at
Bell Services and have them hold your bags while you jump on the complimentary bus to the theme park of your choice! Take a picture of your baggage claim slip just in case you misplace the original copy!
Once you arrive back to your resort after your day in the magic, you can stop by Bell Services and pick up your bags or have them delivered to your room!
Estrella, it is definitely a bit easier when you are staying at a Disney resort collection hotel since they do transfer luggage between resorts when you have a split stay. We always search for availability at the
Disney value resorts when we are adding a day to our vacation.
Have a magical adventure and don't forget to enjoy a Mickey Bar or two!
Kurt