Understanding useDelimiter in Scanner : why I get blank token?

I'm using scanner with delimiter and I've came across a strange behaviour I'd like to understand.

I'm using this programm :

    Scanner sc = new Scanner("Aller à : Navigation, rechercher");
    sc.useDelimiter("\\s+|\\s*\\p{Punct}+\\s*");
    String word="";
    while(sc.hasNext()){
        word = sc.next();
        System.out.println(word);
    }

The output is :

Aller
à

Navigation
rechercher

So first I don't understand why I'm getting a blank token, the documentation says :

Depending upon the type of delimiting pattern, empty tokens may be returned. For example, the pattern "\s+" will return no empty tokens since it matches multiple instances of the delimiter. The delimiting pattern "\s" could return empty tokens since it only passes one space at a time.

I'm using \\s+ so why it returns a blank token?

Then there is an other thing I'd like to understand concerning regex. If I change the delimiter using the "reversed" regex :

    sc.useDelimiter("\\s*\\p{Punct}+\\s*|\\s+");

The output is correct and I get :

Aller
à
Navigation
rechercher

Why it works in the way?

EDIT :

With this case :

    Scanner sc = new Scanner("(23 ou 24 minutes pour les épisodes avec introduction) (approx.)1");
    sc.useDelimiter("\\s*\\p{Punct}+\\s*|\\s+"); //second regex

I still have a blank token between introduction and approx. Is it possible to avoid it?