So... I've fixed the newbie checks which failed with certain dates. This however has brought some changes to the scoreboards as, for example, I was apparently a newbie until last month!
From the code that was already there, and that now behaves as expected, newbies are pipsqueaks that have joined less than 18 months before.
Is this fine? Should we reduce the number of months? (scoreboards are changing anyway :|) Should we add the option to un-newbie-fy oneself? Or change the rule to something like "a whole season"?