Have you tried bringing an additional WEEK(Hire Date) to Rows?
Once you get max, try to convert Discrete.
Create this calc:
That's it. Just index.
Put that on text. See what Tableau sees as the index value for each mark. You want a 1-through-N sequence on index, so you may need to mess with table calc setting for that calc.
Once you get 1-through-N, then make this calc:
IF [index] = 1 then ATTR([rehire week]) END
that will put rehire week only in the first mark. All other marks will contain NULL for this calc and will not display anything. Put that on your text shelf and you'll get the value only on the first mark. (Remove [index] from TEXT once you are satisfied with the results.)
If you had to mess with the table calcs for [index], you'll want to make sure the display calc for rehire week has the same settings.