🎯 Realistic answer

To become strong in Advanced Modern C++:

  • 3–6 months → very strong modern C++ developer
  • 6–12 months → expert-level in practical advanced C++

👉 assuming consistent daily practice


🧠 What “Advanced C++” actually means

Not just syntax.

It means understanding:

✅ Modern C++

  • C++11 → C++20/23
  • move semantics
  • perfect forwarding
  • constexpr
  • templates

✅ Memory & performance

  • allocators
  • cache optimization
  • zero-copy
  • lock-free structures

✅ Concurrency

  • threads
  • atomics
  • futures
  • async design

✅ System-level design

  • scalability
  • APIs
  • low-latency systems

✅ Deep internals

  • object layout
  • vtables
  • ABI
  • compiler optimizations

📅 Best roadmap for YOU

Since you already know C++:

🗓️ Month 1–2

Modern C++

Focus:

  • smart pointers
  • move semantics
  • lambdas
  • STL deep usage

Practice:

  • rewrite old code in modern style

🗓️ Month 3–4

Advanced topics

  • templates
  • TMP basics
  • concurrency
  • memory model

🗓️ Month 5–6

System-level expertise

  • performance profiling
  • async systems
  • low-latency design
  • lock-free queues

🗓️ Month 6+

Expert-level refinement

  • compiler internals
  • assembly awareness
  • advanced design patterns

📚 Best resources

📘 Books

  • Effective Modern C++ — Scott Meyers
  • C++ Concurrency in Action
  • Modern C++ Design

🎥 YouTube / Talks

  • CppCon talks
  • Chandler Carruth talks
  • Herb Sutter talks

⚠️ Important truth

👉 “Expert” is not:

  • memorizing syntax

It is:

  • writing safe, maintainable, performant systems
  • making good trade-offs
  • debugging deep issues

✅ My honest assessment of YOU

With 15 years experience:

  • You can become architect-level advanced modern C++ developer relatively fast
  • Your biggest gain will come from:
    • modern C++
    • distributed systems
    • architecture
    • cloud-native backend design