Dont forget girls like to know a little bit about what to expect, they gotta make themselves look right for whatever is going to happen and also theres the insecurity of being hurt in a place she doesnt know.
Advice I would give myself is consider letting her know what to wear, if you planning on a movie or meal them tell her to dress up

or to wear casual clothes for a bit of an adventure.
Obviously ya dont want to tell her where or what ya got planned but if shes got to dress up then its putting alittle excitement into the event, would YOU be excited/curious if she said to dress smart with a tie.
Have you also said anything to suggest shes gonna be safe with YOU, seems the text suggested just a kids fun day at the playground is in the offing? You got a cool ride planned to pick her up or something to make her wonder what you both gonna be doing?
Just wonder why she should even want to meet you ! - Dont forget shes gonna be testing you, look up bitch tests in these forum posts...
Just think if it was you in her shoes, why should she let you into her

.. have fun whatever happens...
Just my thoughts, advice is free and you are free to take or leave it .
J1f