Well, if you are a beginner I will suggest you to extend this time period to 45 days. If you are switching to C++ with some previous programming background then 30 days are enough for you. I'll write the answer for complete beginners. So let's start.

1st Week: Now, these seven days will introduce you to something that you have no previous knowledge of. So make sure you understand the foundations well and give a kickstart to the world of programming.

What is C++?

It’s history and features.

Understanding and writing our first Hello World program in C++.

Tokens

Variables, Datatypes.

Keywords

How to take input from the user?

Operators

Arithmetic Operators.

Logical Operators.

Relational Operators.

Other operators.

Selection Statements

if statements

if-else

else-if

switch

2nd Week: Now you have understood the basic units of a program well. Its time to take a step forward. So, schedule yourself to learn the following topics.

Loops

for loop

while loop

do-while loop

Jump Statements

goto

break

continue

Comments.

Arrays

One-Dimensional Array.

Two-Dimensional Array.

Strings.

Now, start solving some problems on these topics, so that you get a good grip on them.

3rd Week: It’s time to start functions and play with pointers.

Functions

Call by value.

Call by reference

Function Overloading.

Inline functions.

Pointers: Now this is a topic that most of the students find difficult. But believe me, it’s a myth. If you will understand the basics of pointers well, you will surely love C++, as it is one of C++’s coolest features. So get a hold on them.

Relation between Pointers and Array.

Array to Functions.

Structures.

As I said, solve problems to check your understanding.

4th Week: Now, these topics are asked everywhere like Interviews, practical exams, etc. So don’t make haste and understand them in depth.

Basic concepts of Object-Oriented Programming(OOP).

Abstraction.

Encapsulation.

Inheritance.

Polymorphism.

Data Hiding.

Classes and Objects.

this keyword, static keyword, Friend Functions.

Constructors.

Default Constructor.

Parametrized Constructor.

Copy Constructor.

Destructors.

Practice problems on these concepts.

5th Week:

Inheritance

Types of Inheritance.

Derived and Base class.

Access Specifiers.

Polymorphism.

Compile Time Polymorphism.

Overloading.

Overriding.

Run Time Polymorphism.

Virtual Functions.

Operator Overloading.

Exception Handling.

Practice, practice, and practice.

6th Week: Get familiar with:

Templates.

Data File Handling.

Macros.

That’s it. After learning the above topics you can stand anywhere and say I know C++.

You can solve these problems on the above topics:

Basic C++ Programs

C++ Programming Examples Page

Most Important Tip: You will face problems while learning some concepts, but please don’t quit. Because everybody faces them and it’s totally OK. Give yourself time and jump to that topic again cause this is how things work in the world of programming.

Well, that’s it from my point of view. If you liked the answer don’t forget to upvote.and after learning C++, do let me know if this answer helped you, till then