Thanks for the welcome!
I did start in college. With a language like mandarin because it is so vastly different than English (my mother tounge) I would honestly say fluent is a big word, and I rarely use it. I will say it took me about 3 years of living in the country to become competent.

The reason I phrase it like this is because, even though I participated in a science experiment style talkshow (think bill nye) and had to use '10 dollar words' like 'surface tension, viscosity, and silicone. I still don't know how to say, 'divide' for
Example. Or talk about anything mathematical, because I rarely talk about them in English.

But to answer your question I would really tell myself the more effort you put into studying at the start the easier it will be later on, the times are MUCH more important than you think, learning mandarin will be a never ending process so remember it's not a sprint but a marathon. I have friends who have been learning Chinese for 20 years and STILL learn new words.