It could be Gatekeeper verification that is causing the delay. Take a
look at @RobertHammen's postinstall script
https://www.jamf.com/jamf-nation/discussions/26615/xcode-9-2-deployment#responseChild158119
for the commands in context.
PaperCut & Sierra Known Issues This link references PaperCut Server
rather than client, but it could be possible that the issues with Sierra
and the upgraded version of CUPS also can affect the client depending
upon your system setup. What platform i...
You might try the equivalent of defaults write com.apple.finder
ShowMountedServersOnDesktop 0 on a per-user basis via managed preference
or configuration profile
