It depends on your native language, your concistency, the material you are using and so on.
If you want to learn as fast as possible try to find something that you enjoy doing, if you like watching movies watch movies in the language you are learning, if you like reading, read books in the language you are learning. Be patient.
It could be a week. It could be more than ten years. When you feel your English becomes fluent, you‘ll see it. How fluent it is? It could be Steve Jobs’s level. It could be Trump’s.
If you didin’t satisfy with your English, you would have to keep learning. I’m doing it. That’s why I’m here.
If you need English for your job, I recommend you to have lessons of well-experienced teacher. Learning with movies and YouTube is fun, but I think their English is often too casual.
You can learn from both in the serious lessons and the casual movies. Take them all you can!
I hope my idea helps you, alessio!