https://macmule.com/2015/05/19/making-the-most-of-mac-mini-for-use-with-the-casper-suite/

com.launchdaemon.name.plist

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
	<key>Label</key>
	<string>com.launchdaemon.name</string>
	<key>ProgramArguments</key>
	<array>
		<string>/path/to/rsync/script</string>
	</array>
	<key>RunAtLoad</key>
	<true/>
	<key>StandardErrorPath</key>
	<string>/path/to/error.log</string>
	<key>StandardOutPath</key>
	<string>/path/to/success.log</string>
	<key>StartCalendarInterval</key>
	<dict>
		<key>Hour</key>
		<integer>22</integer>
		<key>Minute</key>
		<integer>0</integer>
		<key>Weekday</key>
		<integer>6</integer>
	</dict>
</dict>
</plist>