Oh, it's never going to be ready for public performance! I am an amateur and I only play for my family and friends and for my own satisfaction. I just started with Mephisto one week ago and wanted to know how I was doing. I also said it was far from finished.
I am really sorry if you got offended(/offensed?) by me! It's not what I meant to do, and I guess I just said what I thought at the moment, which is not nice, so I am sorry. And you also didn't write in this post anything about you being amateur and only begining the piece, so I didn't know that.
Still, I believe that the fact that you are an amateur does not change the picture too much. It may explain a few slips here and there, but overall the performance should be something the listener enjoys.
This piece is considered very difficult, also among professional pianists. I believe the main thing to do right now is bring the piece to a situation that it has some shape and looks like a ready piece, and then of course work on the details. I think you should slow down for now the tempo to one in which you will feel confident about the piece and will not ruin the structure of the piece.
If you start at one tempo, you cannot slow down when it getts harder, everyone will feel it. Just slow down, check all the stops and rhytm so that you don't miss anything. I believe that already would be hard enough. Then, you will have to work on details.
Topic: Liszt mephisto waltz