Welcome Aboard, Bridgid!
How exciting that you are planning your very first Disney Cruise Line vacation! You and your little princess are going to have a royally good time, I'm sure!
There are a couple of considerations for when to book the
Bibbidi Bobbidi Boutique. I see that you are sailing on a 4-Night cruise on the Disney Dream. Your last day is your day at sea, which is when a Princess Party will most likely occur. So, you may want to wait until the evening after your day at Castaway Cay to get your daughter all sparkly and "princessed" up. That way, she will still be made up for the party.
If you are more concerned about her looking regal for the entire cruise, then you might want to head to the BBB as soon as possible once you board. You can book your time online, once your booking window opens up. I know that at the BBB at Walt Disney World, if you bring your own princess dress, you can save that cost.
Some money saving tips:
Purchase Disney gift cards at a local store every time you have a little extra money. You can use these to pay off your shipboard balance when you are on the Dream
Prepay your gratuities before you set sail
Try to limit the souvenirs purchases, or at least have a set budget in mind
Enjoy the drink of the day if you are in the mood for an adult beverage, these are typically around $5
Don't book pricey Port Adventures. The ship has plenty of fun activities that you can participate in, even while it is docked at a port (Our family usually does not leave the ship in Nassau)
Have a DREAMy first cruise!
Happy Cruising, Tracy V.