Hi, Megan!
Thank you very much for sharing your question with us. I love to use
Park Hopper tickets at the Disneyland Resort, and I hope you love them as much as I do. The theme parks are so close to each other that it doesn't even feel like hopping!
If you want to change your first theme park of the day, you must
cancel your existing reservation for Disneyland Park and
make a new one for Disney California Adventure Park. And if you upgrade to a Park Hopper ticket, you will be able to visit your second park after 1:00 p.m., but not before.
But before canceling your Disneyland Park reservation, don't forget to look at the
availability calendar to see if there's availability for Disney California Adventure Park reservations on your desired date.
Please let us know if you have other questions, Megan. We will be here to help if you need anything else!
May the magic be with you,
Julie