If the SCCM Client is stuck on “Waiting to install”, there are a few things you can do. Most of the time a software deployment will be stuck on Waiting to install if another application is installing. SCCM 2012 can also display Waiting to install if a reboot is required.
Check the Installation Status tab of the SCCM Software Center on the client to ensure that other applications aren’t installing ahead of the one that’s stuck waiting. Failing this, try a reboot as a quick fix.
If this doesn’t work, you’ve probably got bigger issues. If you still are stuck waiting to install, you may try reinstalling the SCCM client, testing the install on another computer, repackaging the install or reinstalling the operating system. Check the logs / event viewer for any clues as to why the application deployment is stuck waiting to install.