I am Mongolian. I want to learn Mongolian. I want to study hard, but how long will it take without a language environment?
As long as you have confidence, you will learn it well. Actually, Mongolian is not difficult. Practice your pronunciation and then learn more grammar. Words don't need to be written by rote, which saves a lot of things than Chinese. If you don't know Mongolian at all and there is no environment around you, I suggest you start with Cyrillic Mongolian, which is relatively easy to learn.