Sorry to quote the same passage at you twice, but the best we have for dating this other than the necessary birth of Draco is in chapter 56.

From what Amelia heard, Dumbledore had gotten smarter toward the end of the war, mostly due to Mad-Eye's nonstop nagging; but had relapsed into his foolish mercies the instant Voldemort's body was found.

I don't have a quote to back me, just now, but don't the common folk regard the death of Voldemort as the end of the war? (That's insensitive to Neville's parents, of course, but there it is.)