First thing? Probably not - as I will still be busy telling people how to actually run the program they just wrote. But then, I wouldn't start with use right after "Hello world" anyway. First day of the course? Certainly.

I counted the boilerplate I regularly use in my code. It's at least three lines and often as much as seven,

Exactly. Your boilerplate isn't mine. So, I shouldn't use your boilerplate. Or anyone elses whose boilerplate doesn't match mine. But then, if everyone uses his/her own boilerplate (say, a subset of 10 pragmas), I rather explain 10 pragmas, than having to memorize 1024 different boilerplates. Of course, someone may write a boilerplate pragma that allows you to do:

   use boilerplate qw(strict warnings autodie utf8 mro);
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but that doesn't gain us much, does it?