While there is no exact answer to this question the best answer I can offer you is 2 years if you practice 30 minutes a day based on average expectations but there are definitely ways to decrease this number.
The term ‘deliberate practice’ in terms of guitar practice refers to practicing the guitar in such a way that your practice is meaningful and focused on what matters for improvement. Its very easy to randomly practice different songs or exercises without really having a clear purpose or direction. A good example would be a scale. Your guitar teacher might give you a scale to practice but do you really understand why you are practicing the scale? It may even be possible that a certain scale is a waste of time based on your goals. For example if you want to be a pure blues guitarists practicing a melodic minor scale is probably not the best use of your time if you want to reach your goal sooner rather than later.
Keeping you focused on the 20% that matters
The idea behind G4 Guitar is to reduce the time it takes to learn guitar through efficient practice methods. The Pareto Principle (often called the 80/20 rule) suggests that 80% of results come from 20% of your efforts. G4 Guitar is all about maximising by focusing on the 20% that matters most. The G4 Guitar Method was designed with the end in mind. We know most people have limited time so this makes it even more important to use that time as efficiently as possible. To achieve this we have identified 7 Essential Skills that will help to focus you on what matters most to get you to the required skill level to play your favourite songs faster.