You’ll find the supported syntax here: Creating and Using Templates - #4 by system
\date will insert the current date into the text, unless you use some of the parameters to the choose a different date than today. In this case it sounds like you would want to use \date(for: Thursday). If you don’t provide a parameter (like in: or for:), Agenda assumes what you enter is a date format according to this standard: UTS #35: Unicode LDML: Dates