# Mix date format on pgfgantt, possible?

I would like to do Gantt chart in Latex thus I'm studying http://ftp.math.purdue.edu/mirrors/ctan.org/graphics/pgf/contrib/pgfgantt/pgfgantt.pdf, so far I can do:

The above chart was acomplished by:

\documentclass{article}
\usepackage{pgfgantt}
\begin{document}
\begin{ganttchart}[hgrid,vgrid,time slot format=isodate-yearmonth,time slot unit=month,x unit=10mm
,today=2019-01,today offset=25/31
]{2018-09}{2019-06} \gantttitlecalendar{year, month=shortname} \\


Noting format=isodate-yearmonth allows date to be specified as 2018-12. But sometimes I would like to specify date as 2019-01-25. And I found a way around for today ).
Is there some way around for \ganttmilestone, which will allow me i.e. to do 2019-03-25?