Hi Katrina,
Welcome to planDisney!
Well, this is a planning dilemma we can handle! The good news is that you will be able to visit some parks more than once. There are a few factors that could affect your decision. Let me give a few examples and then we can talk about possibilities.
On our first few trips, my family did not always start our first park day at Magic Kingdom. We typically visited EPCOT because we took a bit of a slower pace on our first day. Lately, though, we prefer to stay at a resort hotel within walking distance of Magic Kingdom, so we will arrive, eat breakfast, and head over to Magic Kingdom. As you decide what to do, consider your travel plans on the first day and your proximity to the closest theme park. Then decide if your arrival day will be a park day. It certainly does not have to be. You could settle in and relax at the resort. Then, start your first park day the next day.
As you make your plans, you also need to check the
Park Hours and the
Extended Evening Theme Park Hours. If a park is open later, we might decide to do that park the day before we have a resort day planned so that we can sleep a little later and just go to the pool. Having said this, we might do the parks in this order - EPCOT, Magic Kingdom, Disney's Hollywood Studios, and Disney's Animal Kingdom, and then we would rotate depending on how many more days we have theme park tickets. If you are staying at a resort hotel close to a theme park, consider visiting that park on your first park day.
Katrina, keep an eye on the park hours, paying particular attending to those extended evening hours. Once those are released for the dates of your visit, it will help you put those park days in place. I will say Magic Kingdom should be first or second. Disney's Hollywood Studios has quite a few attractions so we are often busiest there, especially since we have to catch up with our Resistance allies!
May the Force be with you as you plan!
Magic and memories,
Donyell