Here's my experience of show titles. A title for the show turns up at the very beginning, or you're really going to struggle to think of one you like.
I have a few shows swirling around at the moment. One has a working title that needs to be changed. And another has a title that I don't like any more. Trying to re-title a show is very very hard for a reason I can't quite fathom.
It's worth spending a moment thinking about the point of show title. What is it for? Ultimately, it's the audience's first contact with the show and so needs to be an attention-grabber. But if it's too smart or clever, or too cynically trying to do this, it might sound false or contrived. It should, in some way, encapsulate the show - ideally having a double meaning. But this is easy to get wrong. A slightly lazy way of doing this is using the surname of the 'hero' of the show (eg. Prisoner's Dilemma - John Prisoner is a regular who is always ending up in tricky situations... See? Awful.)
With my radio projects, titles just turned up early on in a fairly pleasing way. Think The Unthinkable was the show title from very early on and conveyed a sense of people advocating change purely for its own sake which is what the show was essentially about. My Bletchley Park sitcom, Hut 33, came along quite easily. Early versions of the show were called Hut 6 (where the likes of Alan Turing worked during World War Two), but then I realised out of respect for those hero-boffins, I wanted a hut that didn't exist and was clearly full of also-rans on the edges. Hut 33 scans quite well and, after I chose it, realised it subconsciously reminds you of of Catch 22. No bad thing (even though Catch 22 is a comedy, but it's such a cultural icon, it feels safe to refer to it in that way). My other short-lived/failed radio sitcom, The Pits, equally came at the start - about musicians in an orchestra pit who were discontent with their lot in life.
In general, it's a nightmare if you have to spend too much time on it. You need a title that sounds exciting and intriguing and is distinctive, but not too weird. But not too bland. I have to say 'New Girl' is a really bland title for a very quirky and interesting show. Felt they could have pushed that harder. But what do they care? The show's a hit.
How do others find this who area of thinking up titles? What are the rules? What are the notable failures, or resounding successes?
(Let's not get sidetracked on episode titles which are largely pointless, and purely to tell them apart in TV listings. That said, the Friends 'The One where...' is pleasing, as is the Big Bang Theory's insistence of using words like Conjecture and Hyphothesis - but they're surely going to run out of abstract nouns sooner or later.)