FitNesse. UserGuide.
TodaysDate [add child]
To diplay todays date:

Markup Text
Displayed as
Today is !today. Today is 02 Sep, 2025.
XML is !today -xml. XML is 2025-09-02T22:27:22.
Right now it is !today -t. Right now it is 02 Sep, 2025 22:27.
Tomorrow is !today +1. Tomorrow is 03 Sep, 2025.
Last week was !today -7. Last week was 26 Aug, 2025.
The month is !today (MMM). The month is Sep.

As you can see, you can add or subtract days. You can include the time tiwh -t. And you can use your own format for the time. (See SimpleDataFormat for the syntax.)