Your first post and it appears you spammed. That's not a good start.
As to your question, some claim you can "Learn C++ in 24 hours" yet I know folk still learning every corner of this language years later. So the answer appears to be from 1 day to years.
How long does it take to walk from New York to Miami? It depends on how fast you walk and how determined you are to get there. How much you learn on the way depends on what you do on the journey.
LearnCpp.com is a free website devoted to teaching you how to program in C++. Whether you’ve had any prior programming experience or not, the tutorials on this site will walk you through all the steps to write, compile, and debug your C++ programs, all with plenty of examples.
Becoming an expert won’t happen overnight, but with a little patience, you’ll get there. And LearnCpp.com will show you the way.
If you find out how long it takes let me know. After 30 years I'm still learning. lol
I think six months of hard work will help start writing simple programs. For two years you can well learn the language and related technologies. And then you have to keep your knowledge relevant and learn all your life)
I'm going to amend my previous comment to "how long does it take to walk to Miami". The answer, of course, depends heavily on your starting point. For someone who has no programming experience, learning C++ will take much longer than someone who has been programming for years in another language. The closer that language is to C++ the easier the learning curve.