Hello,
The update is not available to us either, it is slowly deployed to everyone but not at the same time.
If you want to have it right now, you have to download a script that will put you in the early distribution ring. It is available here : https://gallery.technet.microsoft.com/ConfigMgr-1806-Enable-3eb4b46c
I have not tested the script, I am waiting patiently ;-)
I hope this will help you