Okay, dude I've pretty much been in a very similar situation to you and I ballsed it up so I'll give you my perspective.
Basically, this cute, blonde, fit, sporty girl asked me to her (semi) formal. I was over the moon. Didn't text her too much before the formal, had a good time there I think I was good on the night. Asked her out a few weeks later on the phone, she initially had something on but we set up a time. Went out with her, had a great time (didn't kiss close). Didn't kiss close on the second date either.
My thought process with texting her for the duration of this was this
"She is hot, she is interested in me. I have to show how interesting/exciting I am so that she doesn't drop her interest level or find other guys. By often texting her she will be reminded of attractive I am and how much fun we've had together and thus she will remain interested."
I don't really enjoy texting convos and I honestly ran out of things to say and it resulted in me having crappy boring texting convos with her. My problem was I was too serious in the texts, asking boring 'adult' questions about her family, what she was doing. Honestly, I don't think either of us enjoyed it. For this reason I'd say
Keep it light, edgy and humourous in the texts
I think also it's easy to get sucked in an think that you need to keep texting her to 'keep her IL high' and also, it's a little boost to the ego every time you see a text from her.
For this reason and my own personal experience I would advise
Keep the texting minimum and irregular
I think this line from Hitch is appropriate here.
tonight (all the time), when you're wondering what to say, or how you look, or whether or not she likes you, just remember, she is already out with you. That means she said yes when she could have said no. That means she made a plan when she could have just blown you off. So that means it is no longer your job to try to make her like you. It is your job not to mess it up.
Don't care too much about what she thinks about you. Have a blast at the formal and have a great time with your friends. Because they will still be around after she's gone.