Near-simplest route to learn D

[NonNull]

Hello,

Some documents/books seem to be out of date. If an intuitive 
person competent in several other programming languages and in 
abstract reasoning wanted to take the fastest route to learn 
pretty much the whole of D as it stands now, having already 
learned and used a core of the language, what is the best way to 
proceed? And how long would this likely take?