com.domain.wait.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.domain.wait</string>
	<key>ProgramArguments</key>
	<array>
		<string>/bin/sh</string>
		<string>/usr/local/bin/wait_for_valid_user_to_logon.sh</string>
	</array>
	<key>RunAtLoad</key>
	<true/>
	<key>UserName</key>
	<string>root</string>
</dict>
</plist>

wait_for_valid_user_to_logon.sh

#!/bin/sh

while true; do
  CurrentlyLoggedInUser=$(stat -f %Su /dev/console)
  case "${CurrentlyLoggedInUser}" in
    root|_mbsetupuser|_windowserver)
      /bin/echo "At login window. Sleeping"
      sleep 2
      ;;

    *)
      /bin/echo "${CurrentlyLoggedInUser} logged on. Continuing"
      break
      ;;

  esac
done

# rest of your script here. might need to wait until the Finder and Dock has launched (based on experience you should do this)

until /usr/bin/pgrep -qx Finder; do
  /bin/echo "Waiting for the Finder to load for uomsetup"
  sleep 1
done

until /usr/bin/pgrep -qx Dock; do
  /bin/echo "Waiting for the Dock to load for uomsetup"
  sleep 1
done