How fast can a moderate skilled C++ programmer learn Rust?

I'm currently learning C++ and have finished C++ primer for 2 times, finished 2 books about C++ STL, and have finished C++ concurrency in action, while learning C++ multithreads programming, I know how many pitfalls it have, I have a dream, a dream about designing some massive distributed system for physical simulation and I am pursuing it, after hearing that Rust can let us do concurrency without fear I kind of want to learn some Rust, but in my country, there are little jobs about Rust, so I decided to become a C++ programmer, after acquiring some C++ experience, I can then learn Rust, but how fast can I learn Rust until I can build some projects independently?