This can be easily achieved with the configuration option

Start page = ?sort=<attribute>

or

Start page = ?rsort=<attribute>

where <attribute> is your date.

In your case, you need the URL

http://www.familienhund.ch:8080/Aktuelles+Programm/?sort=Datum+wann

which can be obtained via

Start page = ?sort=Datum+wann