Have you tried customizing org-agenda-format-date with a function?  Here's
the doc string:

"Format string for displaying dates in the agenda.
Used by the daily/weekly agenda and by the timeline.  This should be
a format string understood by `format-time-string', or a function returning
the formatted date as a string.  The function must take a single argument,
a calendar-style date list like (month day year)."

If you're mostly concerned about displaying dates, rather than reading them
in, that might do the trick.


-- Bill

On Sun, Aug 23, 2015 at 9:04 PM Nick Dokos <ndokos@gmail.com> wrote:

> Meir Goldenberg <mgoldenbe@gmail.com> writes:
>
> > Two questions:
> >
> > 1. My work week starts on Sunday, so I have:
> >
> > (setq org-agenda-start-on-weekday 0)
> >
> > Now the agenda timeline starts on Sunday as desired. However, it says on
> top "Week agenda (W34-W35)", i.e. it still thinks that the week starts on
> Monday. Can I change that?
> >
> > 2. It would be very useful for me if the weeks were numbered from the
> week when my big work project started. Can I have the week numbering
> customized to have W01 on a certain date?
> >
>
> I believe the answer is "no" to both questions: these are ISO week
> numbers and org depends on calendar functions to calculate them.
>
> --
> Nick
>
>
>