When did Little Johnny jokes start?

I haven't been able to track down the source of Little Johnny jokes,
but I did learn an interesting fact. These jokes are common in
Spanish-speaking countries, too! In Spanish, Little Johnny jokes are
called "Chistes de Pepito."

Here's a page of Pepito jokes from Guatemala:

http://www.nortropic.com/pepito/content.html

And some from Cuba:

http://www.casacuba.org/fun_jokes_pepito.html

Even more Pepito jokes in Spanish:

http://www.sandiasdurango.com/pepito.htm

http://www.geocities.com/jorgedelatorre.geo/chistes/pepito.html