Setting login screen to username and password – change doesn’t take effect until at least one login

Have a first boot script that sets the login screen to username and password - but doesn't take effect until after at least one user has logged in and logged out. Not sure why this is. Current command is part of a post flight on a pkg that's installed when InstaDMG is run. [code]defaults write "${PREFS_DIR}/com.apple.loginwindow" SHOWFULLNAME -bool YES[/code] Since this is a plist setting - and the prefs_dir is set to $3/Library/Preferences - does that mean that it's installing this as a user PLIST and that's why I have to login first to see it take effect?