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

Markup Text
Displayed as
Today is !today. Today is 23 Jun, 2025.
XML is !today -xml. XML is 2025-06-23T13:03:49.
Right now it is !today -t. Right now it is 23 Jun, 2025 13:03.
Tomorrow is !today +1. Tomorrow is 24 Jun, 2025.
Last week was !today -7. Last week was 16 Jun, 2025.
The month is !today (MMM). The month is Jun.

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.)