They announce it in the press release at the end of the week. It does not count in the DVD sales.
I've never seen a Blu-ray chart for Oricon but I know that they do track it.
IIRC, there's a few places including Phile-soft (a division of SoundScan?) that track Blu-ray rankings on a weekly basis only.
http://www.phileweb.com/ranking/bd-top20/
http://www.jbook.co.jp/p/p.aspx/bun_realrank_12/
The Blu-ray isn't selling as well as I thought it would~