One trait of a good developer is a person that can write code, not copy and paste it only. Or at least doing the former much more than the latter.
I was a copy and paste developer for a long time, relying heavily on Stack Overflow code that I would snatch and then alter to meet the conditions of my own purposes.
Now I’m not saying you can’t do this, but you should reach a point where you can produce a lot of code from scratch, talking through it out loud and actually “writing code.”
You can complete the lessons in sequence, i.e. 12 days, or you can plan to do them every other day, perhaps 3 days a week and complete it all in 4 weeks. It's up to you.
Here's what you should do to get the maximum benefit of this book:
• Do the exercises in your browser console, preferably Chrome. . It's a wonderful place that you should become acquainted with.
• Devote 20 minutes of undivided attention to each lesson. Get the feel of typing that method, that array, that syntax from scratch. Build that muscle memory. Get the feel of what the parameters do. Try out your own combinations and tests until 20 minutes is up.
• Continue on your predetermined schedule until the book is done.
A PDF copy of the book as well as a Cheatsheet to print out and hang up by your desk to easily reference all that you learned in the book.