Hi Angie,
You are correct. There are no Extra Magic Hours in the Magic Kingdom on Monday, June 20th. The park is scheduled to close at 11 pm. You can see that day's schedule
here. During your stay, the Magic Kingdom has Extra Magic Hours in the morning on Tuesday, June 21st and on Thursday, June 23rd. The park is open until 2 am for Disney resort guests on Sunday, June 19th.
The park that does have Extra Magic Hours on Monday, June 20th is Disney's Hollywood Studios. They are open an extra three hours that evening until 10 pm for Disney resort guests.
It sounds like you've done a great job researching your upcoming trip. I'll keep my fingers crossed that your trip is sprinkled with heaping doses of Disney magic and plenty of extra pixie dust.
Thanks so much for your question. I hope this response allays any concerns you may have had about your advanced dining reservations.
Jill