Print message AFTER shutdown completes?

I am using a bash script with the shutdown command to halt my system. I know that shutdown can print a message as an argument. Here's my current command: shutdown -h now "Shutdown complete. You may now unplug the power." However, this prints my message *before* the shutdown command does its thing, and so I see a ton of other messages afterwards, such as "INIT: Sending processes the TERM signal" and "Unmounting local filesystems..." I want to print a final message at the end of the halt, so that the user knows when it is safe to unplug the power. How can I do this? (I am on an embedded system running Petalinux 2019.1.)