How to start writing a project without losing too much time?

Question

Work organization

So I have an idea (in my head) for creating programs.
There will be two programs (closely related to each other):

• For the admin - global settings, database, etc.
  
• For users - everything else not related to the admin part ...
  

And so the question arises: how, what, why, why ...

1. How to transfer the project from head to paper?
   
2. How to transfer a project from paper to scrum, kanban?
   
3. What i.p. choose(How to choose?)?
   
4. Where to start (How to start the code?)?
   
5. How to think about the modularity of the program?
   
6. How to do it right so as not to rewrite the code?
   
7. How to calculate everything so as not to waste extra time?
   

It will not be superfluous to find out how projects are made in Companies / Firms (!!!ATTENTION!!! Not in web studios !!!ATTENTION!!!)

Answer 1

JUST DO IT

Answer 2

1. Write a TK for yourself. Do 1,2,3...
2. In general, these are team methods, you need to choose a time (duration, for example, a week) and assign a sprint to it
3. The one you know best
4. Write a router, or download and adapt
5. This is an art, but in general to apply OOP, to break everything into small functions
6,7. This is also an art, you learn it all your life and it doesn’t always work out. In general, it is more efficient to write the first version that would work and then rewrite it than to write everything "correctly" from the very beginning.

Answer 3

Start by looking for a person who understands all this and is sufficiently qualified.
Entrust him with the choice of language, etc.
Or rather, the choice of developers who will be affordable for you, and then decide what language they know;)
Detailed to the smallest detail to prescribe all the functionality in advance.

How to transfer a project from paper to scrum, agile, kanban?
...
How to calculate everything so as not to waste extra time?

Once again: contact a highly qualified person.
You do not even understand that you are writing downright contradictory things.
The job of scrum/agile is to deliver results quickly.
Make changes quickly.
Modify, rewrite what is written.
And not at all what you want - do not redo anything.

Answer 4

1. Draw on paper. This is not a joke - take a pencil and an A4 sheet and draw until you can explain the essence to some person ...
2. Take the drawing from item 1 and decompose.
3. According to the specifics of the functionality.
4. First, the main module and the minimum functionality.
5. see item 2
6. Don't be afraid to rewrite the code.
7. see item 2

Answer 5

1. How to transfer the project from head to paper? - And why do you need this extra action?
2. How to transfer a project from paper to scrum, kanban? - And this. What is their purpose?
4. Where to start (How to start the code?)? - Launch the editor and start writing code.
5. How to think about the modularity of the program? - And this is also for what?
6. How to do it right so as not to rewrite the code? - That's right, this is when the client is satisfied with the functionality of the application, even if the most terrible code is hidden behind all this. Now, if you work in a team and you need others to easily understand and support this, then you should think about it.
7. How to calculate everything so as not to waste extra time? - This is the same extra item that wastes your time, like most of the above.