Everyone knows that hard work is the key to success. And without mastering a field it is nearly impossible to have a remarkable success.
Many psychological studies has already revealed that 10000 hours practice is required to build a good skill and knowledge in any field. Although this theory is not widely accepted as some people have achieved a good command of their respective field in short span of time. But this theory is considered true for most of the people.
So, if a person wants to be a good guitar player, he/she must have practiced it for more than 10000 hours.   Same goes for other fields such as singing, drawing, solving mathematical problems or having programming skills.
So we need only 10000 hours right? But this is not that much easy.
Let's have a calculation.
If you want to master any single field within one year, you need to practice 10000/365 = 27.39 hours a day. Unfortunately we have only 24 hours in a day. So, this is not possible.
What If we want 2 year?
Again we can divide 10000 / ( 365 x2) =  13.6 hours.
If you can discard all gadgets, all family functions and get togethers, it is possible.
But the most viable solution I've found is the five year plan, which will require almost 6 hours a day.
Even if we can't allocate 6 hours in a day, we can switch to three hours a day, plan, and probably the entire process will last for 10 year

So, what are you waiting for? Choose a best field for you and start practicing from right today onwards.
I'd you postpone for just a single day, your Dre career will start one day later. And if you miss one year, it will postponed for one year.  Just think about it