I/L Freezing Breath

Do all bosses have the same bind-immunity duration? And does it kick in as soon as its bound or after its bound?

Yes, it's 60 seconds starting from when it was bound.

Or maybe it's after. It's been a while since I've done multiple binds. But then, you'd be able to bind right before the last one ended, no? And I'm pretty sure you can bind bosses indefinitely by using one bind from each group, which would only be possible if the immunity starts right when it's bound.