Hi Daryl! Thanks for bringing your question to planDisney.
A 3-day
Park Hopper admission ticket purchased through Disneyland Resort will require you to make your
theme park reservations at the time of purchase. The good news is that you can easily
modify those theme park reservations without paying a fee. The only requirement for modifying a reservation is that theme park reservations are available for your new preferred date and park. It's worth noting that parks and dates can fill up, so the earlier you make an adjustment, the better. This is especially true at popular times of the year, and the
Holidays at the Disneyland Resort are one of the most festive times of the year, making them a coveted time to visit.
When you're selecting your theme park reservation date, you'll also be choosing a park. With Park Hopper, that's the park you're starting your day in, but you can hop to the other park later in the day and even hop back if you want. There's a lot of flexibility there, which my family loves. I think you'll be happy with your Park Hopper selection.
One last thing: terms indicate that your admission ticket must be used within 13 days of the first use. So, you'll want to make sure if you visit on the 15th, for example, that you plan for your remaining two park reservations to fall within the remaining window. Once the window has closed, the remaining days on your admission ticket will no longer be valid. I wouldn't attempt to modify my plans at the last minute for fear that theme park reservations would be unavailable, leaving me unable to use my remaining days within the window of valid use. That would be a not very magical experience.
I hope this helps!
Elizabeth