@TW_Tones created a different version, which calculates the new title using a wikitext function.
See: Problems setting title of a newly created tiddler - #20 by TW_Tones
\function next-title() [range[1],[99]] +[pad[2]addprefix[-]addprefix<now YYYY0MM0DD>!has[title]] +[first[]]
<$button>
<$action-createtiddler $basetitle={{{ [function[next-title]] }}} tags="test" text="content">
<$action-navigate $to=<<createTiddler-title>>/>
</$action-createtiddler>
Create Tiddler and Navigate
</$button>
Or
\function next-title() [range[1],[99]] +[pad[2]addprefix[-]addprefix<now YYYY0MM0DD>!has[title]] +[first[]]
<$button>
<$action-createtiddler $basetitle=`${ [function[next-title]] }$` tags="test" text="content">
<$action-navigate $to=<<createTiddler-title>>/>
Create Tiddler
</$button>