Here's my problem, if my memory is still working right, in the comics there has never been any official revelation about who Joker was before he became the Joker.
yes we have the jack Napier origin from the Tim Burton movie, and jack Napier was mentioned once in a Batman TAS episode by a Dr at Arkham. However last I checked that is not official canon to the Joker's history in the comics.
Joker has stated in the past that he likes to remember his life in multiple choice. Everything he states about his past is a lie.
Supposedly in Death of the Family when Batman faced down Joker he told Joker that he knew who he was, and Joker did a swan dive off a ledge in the batcave. However there is still no official revelation of who the Joker was before he was the Joker, except for being the Red Hood or part of the Red Hood gang.
Thus I think that a reveal of a pre-Joker face, or pre-Joker name would be a bad idea on the show. If they want to have the Red Hood gang that is fine, if they want to have a Red Hood that is fine. That doesn't mean that any one calling himself the Red Hood at this early point in time is the one that becomes the Joker. But the Red Hood's face and name must not be revealed, just like for years in the Spidey comics we did not know that Roderick Kingsley was the true Hobgoblin
Also the thought that Gordon is going to suit up as Batman until Bruce is old enough is just plain dumb. Those that want to spread that rumor should be ignored.
remember though that this is like Smallsville, another reality, and NOT directly tied into either movies or the comics, so Gordon could don the suit, and Joker be revealed early on!