I'll use the recent Luigi album for example:
http://www.nintendo.co.jp/luigi/sound/index.html
They were more specific here and provided two dates, one for when they started taking orders and one for when they started shipping. I considered the latter date to be the release date. The recent Wind Waker album started taking orders in late September but it was around a month before anyone received their copy because it took Nintendo around 3 weeks to start shipping anything.
If Nintendo isn't shipping something to
anyone on the release date then how can that something be considered released?