What do you think of 'Pim' short for 'Imogen'?

Florence and Imogen are both gorgeous, I guess I just don't get the reasoning for coming up with nicknames before the babies are born. Nicknames usually come about organically; what if you daughter likes being called Imogen? I personally think Florence is much nicer than Flo, and Pim makes no sense for Imogen. If you're dead set on a nickname, why not Ginny?