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

Markup Text
Displayed as
Today is !today. Today is 31 Jan, 2026.
XML is !today -xml. XML is 2026-01-31T02:50:48.
Right now it is !today -t. Right now it is 31 Jan, 2026 02:50.
Tomorrow is !today +1. Tomorrow is 01 Feb, 2026.
Last week was !today -7. Last week was 24 Jan, 2026.
The month is !today (MMM). The month is Jan.

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.)