As I am working with the polonaise myself right now, I must strongly advise you against practicing it 3 hours a day, 7 days a week for the upcoming 6 months.
That is not smart at all, it is insanity. 1. The piece is so physically demanding, especially when you find it technically difficult, that you will most likely risk injuries. 2. You will also get mentally exhausted and damage the musical interpretation.
So I recommend that you spend far less time learning this piece. I doubt that your progress will be slower this way, on the contrary.
If you really like practicing 8 hours a day, then by all means, do so and be happy (but please listen to your body as well - you MUST NOT play if you feel pain and/fatigue because that could get you in big trouble). But spend these hours with a lot of different pieces and exercises. That will make you a much better pianist and you will eventually learn faster.
Personally I think competitions are just crap from an artistical and musical point of view, just as stupid as beauty contests. Either you want to be an artist, or you want to win competitions. Of course you can do both - I know many who do - but really, make up your mind on what is your FIRST priority. Yes, go for the competition if that amuses you, but ... the key word here is that it should be FUN.
Really. If playing is not fun, there is no point in it. You say that willpower is the strongest thing and I say you are wrong. It is nothing. I would not even recommend such a rigorous schedule as you suggest, because development is not about working through so and so many hours. I know what tradition says. It says that no pain, no gain, and if you want to be successful you must STRUGGLE, use a lot of SELF-DISCIPLINE and WILLPOWER. That is the only way to go, right? No, I am bold enough to claim that this is wrong. Listen, you are not Evgeny Kissin, and you are not Arthur Rubinstein. You are Daniel. You have to develop Daniel, this is the pianist you are meant to be. And how do you do that? Well, it is rather easy: just follow your own desire, focus on having fun. One day you want to play for 9 hours, one day you don't want to play at all. One day you want to play this, then something else, then you want to just listen to someone else or whatever. DO WHAT YOU WANT TO DO. To become YOU, you should not have to push yourself at all.
You might think that this attitude is highly irresponsible and that everybody who follows it will become slackers and non-achievers. In fact, this is not true at all. Most of us want to do things, good things. If we do things we really love to do, we can work very diligently. Nobody works harder than a person who is in the flow!
I am also convinced that the world would see many more great pianists if more piano students followed their heart instead of traditional patterns. I have seen many pianists who play technically brilliantly, but they are painful to watch because they look like they are suffering, like they are not enjoying what they are doing. And of course they are not, because they are nervous. They are too busy performing so they forget to PLAY. It is fun that the English word "play" means two things, right? Or ... does it? We have also seen musicians, great musicians, who are so in love with their music and their piano that they shine. Not only do they produce wonderful music, they also gain a lot of fans because it is such a pleasure to attend their concerts and share the moment with them.
Well, so how do you win a competition, then? Don't ask me, because I don't know. But I know that the happy pianists are the most successful in long terms. Some of them participate and win contests, some of them ... never do. So what I try to say here is simply that you should not ignore your feelings when you practice. Starting with a schedule is ... well, that is a good start, but never push yourself if it starts to feel uncomfortable. Let your instincts, that is, your feelings, guide you and you will become the best pianist that Daniel can possibly be. Again, I think your plans for the polonaise are far too hard. You don't want to end up hating this brilliant piece of music, do you ...
Topic: Am I being too ambitious? Can I achieve this?