Agree with the pp that crowds should be a bit lighter with your earlier dates. Parks will still be crowded, but should not be so densely packed.
Do your research, make your plans, make your backup plans, then get ready to let go and let the magic happen! If you want dining packages (highly suggested if you will want to see F! and if WOC is back up and running at that point), make your reservations as soon as the dates open for you (60 days in advance, usually-but-not-always). Same for any TS dining reservations you'd like. Otherwise be prepared to eat at off peak hours to avoid the longest lines. Bring lots of patience and a positive attitude, make sure to get your "First Visit" buttons (City Hall, Chamber of Commerce, most stores at the registers, some CMs), and get ready to enjoy the magic! (And take lots of photos -- this trip is going to make so many memories for your family!)