I don't know, I really believe both kids would be unbelievably excited and wouldn't get hung up on what I packed for them and just be grateful we were going

They're really amazing kids. They have never been anywhere, we haven't ever been financially in a position to do anything even close to this, and we always dream together about Disney and what it will be like when we "finally get there"

. I want to make it a big surprise they'll always remember. They are dying to take a plane ride and They LOVE surprises. Maybe telling them the day before does make more sense, and then they can pack with me but I'm not sure yet
I LOVE the idea of playing When You Wish Upon a Star to get them up!! I'm going to do that no matter what! Thank you!
My (then) 13 year old 8th grader loved being surprised and wouldn't have cared one little bit if I would have packed him a suitcase full of underwear when we surprised him.
Do the surprise! And do it as close to the time you leave as possible. Our flight/airport arrival times coincided perfectly with our normal morning routine, so we were able to literally wait until the kids were ready to walk out the door for school when we sat them down and pulled out the goody bags that included their magic bands and boarding passes. 15 minutes later the limo we hired to take us to the airport pulled up. The kids had time to grab one item of their choosing and everything else was packed. So what if you didn't pack everything...it's not like you will be gone forever! They can live without something for a week!
I love the "Wish Upon a Star" as the wakeup....even at that hour, at 14 and 8, they will love it once they "get" what is going on!
And we never lied to our kids at all...as a matter of fact we pretty much told them over and over again in hints and cryptic clues and they ever caught on! It was part of the fun to say something like "I know it's cold today, but just imagine what it would be like if you woke up next week and you were laying by the side of a warn, sunny pool", or "Look at the plane...I wish I was on a plane going somewhere right now! Oh, well, maybe someday soon!" And, the morning of...."Oh, I haven't left for work yet because my boss told me I could change my schedule this week"

It was even MORE fun the whole week we were there because the kids kept asking about their teachers, friends, babysitter, grandparents, etc....they were ALL in on the surprise and it was so funny watching the kids as it started dawning on them how many people knew and they didn't! My 8 year old was especially tickled to hear that his beloved teacher asked if she could go with us!

I am pretty diligent about details, so I worked through every potential issue and talked to all the teachers...we did wait until after football/cheer season was over so it was in a "downtime" period for my kids' sports just because we are big believers in not pulling our kids from team sports during the season.
My 8th grader was totally fine with missing school. As he said "Mom, there isn't anything that is THAT important that I cannot make it up. I would do double homework for a month to be able to go on a trip!"
The only downside is that now our kids are totally ruined. Every time they think I am hinting at something, they think I'm about to make a huge announcement LOL I have to start a lot of conversations with "This is not a trip to Disney, but...." Haha
Sometimes people post here about surprises like they are surprising their kids with a trip to the hospital for brain surgery. Other than a few minutes where a surprise might not go exactly as planned, I can't imagine, (special needs aside) any kid being so tightly wound that they need to "wrap their head" around a surprise so much that they flip out like the world is ending...geesh. Go with the flow and enjoy Disneyworld, for goodness sake!
If you want the details of what we did, search my posts - I think I just posted about this about a week or two ago. Or just ask! My kids were 13, 10, and 8 when we surprised them, and all three have begged for the past 2 years now for us to do it again!