These gentle men are absolutely correct, however, I would not start out practicing 2 hrs. a day. You will probably want to practice all night, but if I were you I would break into casually. Practice maybe 15 mins a day starting the first week. If you are suffering Guitarise and can't help yourself, practice 15 mins. twice a day. Like one session in the afternoon and the 2nd session later in the evening. If you try to do too much to soon, you will be so sore that you will not be able to play correctly and playing correctly is a must.
After the first week, add another 5mins., the third week add 10mins., the forth week add 15mins, and so on and on. Your goal is to practice 2 hrs. a day. It will be boring at first, because it's the same thing over and over, but after you build up your calliousises (Spelling ???) and finger muscles and start playing songs, you will get more and more excited and practicing will go easier.
Don't miss a day if it can be helped. It's important you practice every day even if only for your orginally 15 mins.
Also, I would try to get an instructor who teaches all kinds of music. A good instructor just doesn't teach one type. You may enjoy listening to one kind of music, but when you start playing and are exposed to different types from the playing end, you may find you like something better or just as well. A good guitarist can play anything. Don't limit yourself. Also, if you start playing gigs your customer may prefer different music or atleast to throw in his favorite song, etc.
Mr. Sasuke199 is correct. A good instructor is hard to find. If your instructor isn't doing the job, you can always find another. There are a lot of them out there, but there are a lot more that are not so good. As Mr. Sasuke199 implied, a good guitarist may not be a good instructor. You need one that is both.
Don't worry about starting at age 23, as if that was old. Man! To be 23 again. Anyway, the best time to start is now!
Good Luck!