If you change the silent switch to "silent" while the iPhone is fully off, when you turn on the iPhone the "silent" indicator does not appear.
I admit I did not wait 30 seconds, because having to wait makes it unusable.
I removed it, I will try it again some time if the developer finds a way to get it working faster.
Note: Erica Utilities and sqlite are needed. Make sure these are installed, or Cydia installs with this app. A complete phone reboot is necessary. Also, it could be as long as 60 seconds for the status to change. If you need it faster, insist Apple build this into the phone where really belongs.