There is really no way to say how long it will take to get to 4.0 watts/kg since everyone is different. Your rate of improvement is dependent on many factors, including genetics, build, available recovery time, quality and consistency of training, etc.
Many of these factors are outside of your control, which is what makes Outcome-Related goals a bit tough to manage. When trying to improve, it is good to make Process-Oriented sub-goals that will help you work your way towards your Outcome-Related goal. Essentially, these goals should encompass all of the factors within your power. For example:
Make a goal to
- Stay unwaveringly consistent in your training. Barring sickness, try to choose a plan and stick to it. This will be the biggest contributor to your success.
- Focus on good nutrition. Eat whole, nutrient-rich foods whenever you can. Avoid “junk food” and highly processed foods. By optimizing your nutrition, you can improve the “kg” part of the equation.
- Be sure to get adequate rest and recovery. This is just as important as the hours spent on the bike.
- Add any other sub-goal that you think will be a contributor to your success
Write these goals down so that they are solidified and real in your mind.
By doing this, you focus on the steps you need to take to get to where you want to go. You focus on the variables in your control. You become in control of your own self-defined success. These variables, combined with variables outside of your control (like age, genetics, etc) will determine how quickly you improve and see progress.
As for what volume you should do, that depends on how much time you have available to train and recover. The Mid-Volume plan is fairly attainable for most athletes, however, this will depend on their lifestyle. In order for training to have a positive effect, you need to take time to recover. If you are constantly on the go and fitting in your rides in the only spare hour of your day, then you may not be able to handle Mid-volume. On the other hand, if you have some leisure/ relaxation time in your say, then Mid-Volume could work well.
It is very important to listen to your body as you work through the plan and take the necessary actions in response to those signals. If you feel under-worked, maybe you need to bump up in Volume. If you are feeling overworked and fatigued, then maybe you need to bump it down. Remember that selecting a plan that is too much for you to manage it is not going to benefit you in the long run.
I hope this helps!