He did finish it.
My advice: start writing your material now, as if it were a humor essay you were going to send to a magazine or whatever. Obviously you won't speak like you write, but it's important to produce a routine, i.e. something you know cold. When you've got some material, speak it and record it, either audio or (better if you can do it) with video. Constantly analyze and reanalyze it, and edit every single word you can. Try to shoot for just under three minutes or just under five minutes, since when you perform (if you're any good) you will have to account for the audience laughing. This is important because any strict "amateur nights" will give you three or five minutes exactly, and they don't [censored] around. Also, if you get noticed, you'll be asked to open (at my local club these guys are called the DJs; I don't know if that's a universal reference, though) who gets three or five minutes and introduces the opener who gets 15 minutes, who introduces the headliner who gets 60 or 90 or whatever.