I'd actually recommend a pre-park opening breakfast at Be Our Guest. Touringplans Reservation Finder can help you find one, as well as checking frequently. If your reservation is for before 9 am, you can into the park early. Being there when it's nearly empty is magical.
I'd try to get as close to 8 am as possible, then after breakfast, head to Seven Dwarfs Mine Train. It's a fun, smooth rollercoaster. We were able to ride it once before the park even opened when we did this 2 years ago. If the hours are changed to 8 am opening though this isn't possible and the reservation isn't worth it. Lunch would be a better choice in that case.
The rest really depends on what FP+ you're able to get and what you both are into! Splash Mountain, Big Thunder Mountain, and Space Mountain are the bigger rides that you'll want to catch early or have a FP+ for. Peter Pan's Flight isn't a thrilling ride but it's magical to me and popular with kids. It's A Small World. The Haunted Mansion is definitely an iconic must-ride.
I'd plan shows for the afternoon if it's hot and to rest, try to book additional fastpasses for after, grab some food, and then enjoy the evening there. Don't be afraid to take a break in the park such as at Tom Sawyer's Island to rest without leaving! Jungle Cruise. Pirates of the Caribbean is best at night to me. I also like the Astro Orbiter at night though the height scares me a little. Look through the rides and shows and pick a couple must-dos! Make those the priority and have some "if we feel like it" plans as well, but don't force it and enjoy the moment.

There are also characters as well if your daughter would like that.
Find a spot to relax for the parades and fireworks, maybe with an icecream and if you're not exhausted, wait out the crowds leaving. It'll be much more peaceful leaving if you just sit until it calms down a bit. But make sure to rest mid-day if you want to make it this far!
Also, if you want to do a table service meal, I'd recommend 1-3 for the rest and waits will be pretty high then, and possibly hottest part of the day. Could be any temperature in March in Florida.
I hope it's magical for both of you ❤