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

Markup Text
Displayed as
Today is !today. Today is 25 Mar, 2026.
XML is !today -xml. XML is 2026-03-25T15:14:37.
Right now it is !today -t. Right now it is 25 Mar, 2026 15:14.
Tomorrow is !today +1. Tomorrow is 26 Mar, 2026.
Last week was !today -7. Last week was 18 Mar, 2026.
The month is !today (MMM). The month is Mar.

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.)