Here's my dilemma, I'm new to Acrobat. I learned how to make the stamp, and have a stamp ready to make a dynamic stamp with the date field. My hang up is when you say "add the text form field that includes the custom calculation script" how do I do that? That's the missing piece. When I search for adding text to stamp, the instructions have tools I don't have like document processing and the customize button. Is there a tutorial specific to Acrobat DC for a newbie? Also, in DC I don't see where to edit a stamp. The closest I find is below, and it's pretty limited

To edit a stamp, you need to know where it is stored as a PDF file (all stamps are stored in PDF files with one or more pages, and the actual stamp pages identified as "page templates"). There are two options for where these stamps are stored: In the user level stamp directory, or the application level stamp directory. Where these directories are depends on your version of Acrobat, your operating system (and version), and the type of computer you are using (32 bit or 64 bit).
Let's assume you are using Acrobat 11 on Windows 7, 8 or 10, then the user level directory would be this:
C:\Users\<your user name>\AppData\Roaming\Adobe\Acrobat\11.0\Stamps
The application level directory would be (this is for a 32 bit system - the 64bit system would reference "Program Files (x86)"):
C:\Program Files\Adobe\Acrobat 11.0\Acrobat\plug_ins\Annotations\Stamps\ENU
Your stamp files will have cryptic names when you created them via Acrobat's stamp tool (and, in that case, they would also be located in the user level directory).
To add a form field with Adobe Acrobat DC, you would need to start the form editor after loading the stamp file. You do that via Tools>Prepare Form" - once active, you will find the different form fields on the toolbar:

Once you've added a field, you can bring up it's properties via right-clicking on the field (that assumes that the form editor is still active), and selecting "Properties" from the menu. After that, you should be able to add your date script as a custom calculation script on the "Calculate" tab.