I'm in no way proficient but I am a TA for an entry level OOP course at an UC. It took me 2 weeks to read through the major topics in Rust. And another month to get a good hold by gradually writing bunch of code.

I am in no way proficient, but I've been using it casually for about a year. I'm just now starting to feel really comfortable with it.

I've been coding Rust for three years in my free time and I'm still working on it.