Lately I have been getting this question from students a lot especially on their first acoustic guitar lesson. "How long should I practice?"
Well the answer to that question depends on one of two things. Do you want to master the instrument or do you just want to learn to play it for fun? They say, (whoever they are) that the guitar is the easiest instrument to learn to play and the hardest to master.
If you want to "Master" the guitar then you should need approximately 10000 hours of practice and you can stop reading this article right now.
If you are amongst the millions of people who want to learn for their personal enjoyment and to have a good time with their friends things are different. I believe that in just 48 hours you can learn the basics that will enable you to do exactly that. When I say 48 hours I mean a 48 hours of dedicated and focused practice, and no just goofing around jamming a few chords the wrong way. You should have a proper acoustic guitar lesson or tutorials and have a specific practice routine. I suggest a minimum of 30 minutes a day 6 days a week and in just 4 months you should be able to achieve your goal.
Four months are enough for you to learn all the basic theory, rhythms and all the chords you'll need to play some easy guitar songs.
Consistency is more important than the amount of time you practice. What I mean by that is that it's better to practice a little bit every day than once or twice a week for a long time. Trough repetition we learn muscle memory and in a nut shell that is the trick. So practice a little bit everyday and keep up the routine.
Don't let the simplicity of this tip fool you, it works!