the option is currently named --delay-hosts

howto/upgrades.md

@@ -258,7 +258,7 @@ be changed to *30 minutes* if the hosts are part of a mirror network
 to give the monitoring systems (`mini-nag`) time to rotate the hosts
 in and out of DNS:
 
-    ./reboot -H mirror-01.torproject.org,mirror-02.torproject.org --delay-nodes 1800
+    ./reboot -H mirror-01.torproject.org,mirror-02.torproject.org --delay-hosts 1800
 
 If the host has an encrypted filesystem and is hooked up with Mandos, it
 will return automatically. Otherwise it might need a password to be