I heard around September.
EDIT: Well, I heard that Hetalia Season 5, or known as Hetalia The Beautiful World, is starting on Friday January 25, 2013. and even on the trailer, it said (in Jpaneese) January. In numeral, it said 28, 2013. And since in Japan, they're a day ahead of us, so technically Hetalia The Beautiful World is airring its first episode January 25 ,2013. I hope this helped.