A common question asked is how long until you're good on guitar? How much practice until I'm fast? Etc.
Well, there is no answer. There are too many varying factors involved to ever give a specific answer.
To help you gauge your progress, I invite you to write down what you do. For example:
Let's say you have 3 exercises you are trying to get fast at. Write down what the exercise is, or name it, and then write next to it how fast you get on the metronome with the exercise. Every time you finish a practice session, write down your highest speed. This will give you a clear way of seeing how you're progressing.
I invite you to only compare your progress to your own progress. In other words, don't compare yourself to others. We all have different factors that help develop us in becoming musicians. Even something like where you live, your family, your job, etc. can also make a sizable impact on how you can develop.
As long as you stay persistent, practice daily, and just keep trying to improve, you will definitely improve. Only when you quit trying is when you will never make progress. Keep playing!
John Taylor - guitar and bass instructor for Mile High Shred.