There is no shortcut, if you wish to learn to play guitar. This is a slow process and requires constant practice. No matter if you are a self learner or you have hired a professional guitar trainer. If you do not have time to practice then probably you should not waste your time an money in learning guitar. However, depending upon the style that you wish to learn to play, it may take between 6-8 months to learn the basic scales and Chords. You should be able to play few songs after you have practiced enough. Upto 2 years, if you wish to master the Scales and upto 5 years if you want to master the guitar fretboard and wants to play by ear. Remember that everone has different learning skills and some has born musical talent so this can be an added advantage in learning faster if you have good ears. Also, people who sing as well be an advantage in learning this instument faster. This all will come in handy only if you practice. Remember, No shortcuts. Least say, if you just want to learn few chords and start playing some songs without any music understanding then this could be achieved within few months. (Good News). So, before you start learning, decide wisely what you want to learn. Do you want to learn just few songs or you want to play guitar like a Pro !
6-8 months (Basic Music Theory, Finger Movement exercise, Major Scale, Major Chord, Major Scale Chord Progression, Major Songs)
2 years (Major, Minor Scale, Minor Scale, Minor Scale Chord progression, Minor Scale Songs,Staff Notation)
4-5 years ( Pentatonic Scales, Blues, Raagas on Guitar, Arpeggios, Solos, Hammer, Pull Off-Pull ON, Sliding, Suspended chords, Major-Minor Chord Extension, Finger Style playing, Ear Training, Advanced music Theory,Mastering Staff Notations)
Like I said above, there is no shortcut to learn and master guitar. Still, if you are practicing an hour daily and you know what you need to practice then within an year you should be able to play few songs to entertain an audience. However, there are lots of techniques how you can play guitar like chord style, finger style, solos, tapping, arpeggios and many more. In order to master all this, this may take 3-5 years. If you want to establish your self as a performer then you should practice more and more. Learning theory does not require a lot of time.
Though it is said that there is no specific time when you want to learn anything in your life as learning never ends However, its my personal view that any one who is more that 5 years old can start learning guitar to make is more confirtable and easy to grasp, I recommend that the learner or the student shoud be or atleast 8 years of age.
Thats very common thing and it happens with everyone. You dont need to worry as it will soon stop hurting within couple of weeks of regular practice. Keep practicing, once your finger tips create some dead cells and becomes firm, you wont feel any pain. Its perfectly normal. However,if its hurting a lot then I will recommend you to stop playing and give it a day or two rest. It is important that you should know the proper technique how a chord, a scale or a fretnote should be played. Playing or handling guitar in an improper manner will cause more issues. Be sure to hire a trainner to guide you.
If you have decided to learn guitar then you should have a Guitar, A CAPO, a Chromatic Tuner, Set of PICS (Thinknes - 0.50 to 0.80), Guitar Cover or Case, Guitar Stand or Wall Mount .