Guest of Honor

How concerned should I be about this email from a school friend's mom that references my 7-year-old daughter:

My son came home today begging me if we PLEASE can invite Molloy to his party on Friday.  As you see from the invitation it was supposed to be a "boy" birthday, but he would love for Molloy to be the female guest of honor.

I know this is very last minute notice, but I hope it works out.

Is there some kind of scientific formula I can use that takes the amount of worry I have today and uses it to calculate the amount of worry I'll have when she turns thirteen?