How early can jails be started?

[Warren Block]

Is it technically possible to start a jail much earlier in the boot 
order?

The reason is that a jailed DNS server could be used by the host if it 
was started before any of the host's network services needed DNS.  After 
/etc/rc.d/netwait, say.

There may be other jailed services that would also benefit from an early 
start, but DNS is something of a special case and the only one that 
comes to mind.