Hi Ashley,
Welcome back to the Disney Parks Moms Panel! You are
my kind of planner. I love playing around with the system and trying out different itineraries and plans, and I hope that you're having a BLAST
planning for your upcoming trip and dreaming big Disney dreams while you're at it!
You're exactly right! If you purchase a 3-day
theme park ticket, you'll have five days from the tickets' start date to experience all of the magic and fun, so in the example you gave, you would be able to save your last theme park day for Friday. Your days do not need to be consecutive either, so you can feel free to visit the parks whenever it works best for you within that
window of time. My family likes to enjoy a day at our
Disney Resort hotel every few days to sleep in, swim in the pool, and enjoy all of the fun recreational activities there. If you'd need even more time to enjoy your theme park days, you do have the option to add the Flexible Dates Option to your tickets which allows you to begin using your tickets at any point between now and December 31, 2020 and it also gives you 14 days to enjoy all of your theme park days.
I hope this helps as you're planning your trip, Ashley, and please feel free to keep your great questions coming. We're always here and happy to help. I hope that you have a truly magical vacation!
Missy