SSHSSH
You'll only see the option AFTER the staging period. As you say above, you'll be able to specifically enable all those signatures in staging that weren't triggered, and underneath you'll see the signatures that were triggered for you to view for false positives and enable / disable accordingly. This option isn't available until the Staging period is finished.
If you do wait 3 weeks then the signatures in staging are kept in non-block mode all that time - but the staging stats don't change to reflect any new hits (or at least I don't recall if they do!).
Rgds
N