Hi Jay,

I'm sorry for the long delay in writing back -- I was travelling and let my email get away from me. I'm doing something kind of similar but not exactly the same.  My problem is a little bit easier -- my dates aleays change by exactly a week, so what I have done is to retain the first date and just iteratively insert timestamps as i go.  So I've written this defun:

                           (date-to-time base-date) (days-to-time (1+ 7)))) ))

Then I have an org file like:

#+MACRO: ts (eval (get-ts+7))

* Week {{{n}}} <2017-09-17 Tue>

* Week {{{n}}} {{{ts}}}

* Week {{{n}}} {{{ts}}}

* Week {{{n}}} {{{ts}}}

You could modify my defun to take a parameter, maybe something like this:

(defun get-ts+7 (plusdays)
    (interactive)
    (let ((base-date "<2017-09-17>")
          (result nil))
    
      (format-time-string "<%Y-%m-%d %a>"
                          (time-add
                           (date-to-time base-date) (days-to-time (1+ plusdays)))) ))

But then you'd need to eval the defun every time. So maybe something like this:

#+MACRO: ts (eval (let ((base-date "<2017-09-17>")(result nil)) (format-time-string "<%Y-%m-%d %a>"(time-add (date-to-time base-date) (days-to-time (1+ plusdays)))) ))