This one goes into the settings to "Apps" and then "All". Look out for the item "Google Services Framework" out and select "delete data". It is possible that some of Google's services are terminated. This is not so bad, so you have to worry about. Then you go back to "Settings" and then click "About phone". Now you click "System Updates" and goes on "Check for updates" on there.
This procedure is then repeated until it works. On the Internet there are many different reports on this method. For some it worked out after the second attempt already, others have taken five to ten startups, and still others was also the 30th Attempt not crowned with success.
Whether it's a chance now that this system works is probably hard to say. For some, the update may actually just arrive in this time when they tried it, who knows. But for the impatient, there is at least worth a try. Even I could not try it, unfortunately, since I got my Nexus Galaxy already had when getting the message that an update is available.