Why does Bond's nickname for Max catch on so quickly?

I could be wrong, but from what I remember Bond didn't really give him that nickname. Max Denbigh (Andrew Scott) presented himself as the new head of (I don't remember which department), and Bond then said [paraphrased] "So I guess I should call you C then". In my interpretation, it meant that within MI6, "C" had always been the nickname for the head of that department, possibly as an abbreviation of "Control". (I think Denbigh's department is tasked with the control, checking and evaluation of other departments such as the 00-section. Maybe there's more about it in Fleming's original stories, but I haven't read any of them.)

Denbigh didn't like the nickname, he wanted to be seen as a modern, amiable/friendly collegial manager rather than as an old-fashioned, impersonal, authoritarian boss, that's why he presented himself with his name. But Bond wanted to keep a cold, professional distance to him, because in his eyes Denbigh is just another authoritarian supervisor who merely tries to come across as modern, friendly and collegial (or maybe Bond simply doesn't like the idea of "a modern boss" at all). And when Denbigh persisted "I'd prefer just 'Denbigh'", Bond sees the fakery and the control-freak behind his cordiality and hence answers, "No, I'm gonna call you C.", with the double meaning in place - because not only is Denbigh just another head of the department that the 00-section is always at odds with, but Bond is now convinced that Denbigh has the character of a snake (hence he deserved to be called the "C-word").

That scene enforced to the audience Bond's no-nonsense, authority-defying demeanor, but also planted the seeds to establish Denbigh as an antagonist.

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Keiko Matsui & Carl Anderson - "A Drop of Water"
http://youtu.be/kPUENUUuqSk

If M repeated it, others would quickly follow.

What no man Can give ya. And none Can take away.