Hi, Steph!
If your darling princess is in any way not excited for the
Bibbidi Bobbidi Boutique experience, I would definitely wait until she is older. While the Fairy Godmothers-In_Training are wonderful, they do have to get quite involved with hair, rubberbands, gels, sprays and such, all which can be overwhelming. Guests can be up to age 12 for this magical make-over, so you have plenty of years to enjoy this particular experience.
In the meantime, stop by the Boutique with your daughter. Let her look around, and she (and you, too!) can even ask for a complimentary sprinkling of pixie dust. This might be a good way for her to see what the Boutique looks like, what the process is, and how much fun her fellow princesses are having. You can then make a better decision when she is a bit older.
Wishing you a magical vacation in
Walt Disney World!
Cathy