NotBefore attribute in the IdP

[Cantor, Scott]

> You'll need to stick this in a RelyingParty element dedicated to any SP that
> would break, and as the Wiki page notes, this really isn't the right fix for the
> problem.  The right fix would be to ensure that the clock doesn't drift again.

You can't fix a broken SP by managing your own clock, it's their bug. Some drift is always going to happen.
 
These features are there to temporarily work around simple bugs while they get fixed.
 
-- Scott