Hi Nicole! Thank you for bringing your question to planDisney.
At this time, all Guests ages 3 and up must have a
Disney Park Pass reservation as well as valid
admission to enter a theme park. I just took a peek at the
availability calendar and I do see that
Magic Kingdom Park has limited availability over the next week or so. That being said, other Guests' plans change all the time, so keep checking back to see if you can secure a reservation for your son on the same date you scheduled your Disney Park Pass, or perhaps try a different date or different theme park.
If your ticket includes the
Park Hopper Option, you might try reserving a different theme park to begin your day and then "hop" over to Magic Kingdom Park when
park hopping hours begin at 2:00 pm. Disney Park Pass reservations are only required for the first theme park you visit each day; no reservations are required to park hop. (Subject to theme park capacity.)
I do hope that you are able to secure the reservation you need for this weekend. If you have any other questions, please stop by planDisney again.
Anne Marie