Create Custom Dynamic Stamp with Future Date

Hello,

I am trying to create a custom dynamic stamp that posts a future date. For example, when I open my custom stamp on a document I want the date to display 9 days later. I have followed the tutorial on how to create a custom dynamic stamp, but I am unable to find javascript that will work to output a future date.  I have tried looking online for future date javascript that should theoretically work, but it doesn't work in my stamp or just even when I play around with form fields. Can someone please help?

The current date script I have is:

event.value = (new Date()).toString();
AFDate_FormatEx("mmm dd, yyyy");

Thank you,

Lynnette