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

Markup Text
Displayed as
Today is !today. Today is 15 May, 2026.
XML is !today -xml. XML is 2026-05-15T03:52:55.
Right now it is !today -t. Right now it is 15 May, 2026 03:52.
Tomorrow is !today +1. Tomorrow is 16 May, 2026.
Last week was !today -7. Last week was 08 May, 2026.
The month is !today (MMM). The month is May.

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.)