Ambiguous release schedule

[Undead8]

When new versions are released, it is not clear as to when they take effect or when the new binary should be used. For instance, the latest release v1.2.0-rc0 has no indication as to when it takes effect (block height, timestamp?) or if production nodes should upgrade right now or at a later version.

Could you please mention in all the release notes when nodes used in production environment should upgrade to the new binary?