Try getting into Muay Thai or BJJ first. See how you like it. Try some sparing in class and you can be ready to fight in a year.
I've never trained MMA, but I did train Muay Thai, and a lot of the people were fighting within months of joining. Of course, the ones with the better chance of winning had been training for a year or longer.
But more than anything, you need the will and the dedication. Personally, I just do Muay Thai for fitness but as I've come to learn the sport, I've learned a deeper respect for it (and MMA as a result) and am considering taking up some other martial arts to round out my skills for MMA.