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

Markup Text
Displayed as
Today is !today. Today is 16 Oct, 2025.
XML is !today -xml. XML is 2025-10-16T19:01:06.
Right now it is !today -t. Right now it is 16 Oct, 2025 19:01.
Tomorrow is !today +1. Tomorrow is 17 Oct, 2025.
Last week was !today -7. Last week was 09 Oct, 2025.
The month is !today (MMM). The month is Oct.

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.)