I'm sorry but we don't have information on the delivery schedule of the update on any country or operator.
If you went to Settings and then Phone Update and it tells you that there's no update available, it's unlikely that you'll be able to update the device when you connected it to Zune since the update is not yet available at the first place. The best thing to do is to wait until the update becomes available.
Once you connected your device to Zune, it will automatically check for the updates. On Zune, you can also go to > Settings > Device > Update. You can read more here: http://www.windowsphone.com/en-US/How-to/wp7/basic
I have recently bought a lumia 610. I have updated to Win 7.8 and still have the problem people are reporting of drive freezing. It finds the location and plans the route but never starts navigating. Any suggestions?
Same problem with my Lumia 920. After a half year it now freezes since a week., plans a route but does not start navigating
I have done resets and uninstall install without any result.
After updating the phone and then doing a reset the GPS is finally working correctly on my lumia 610. I have noticed it can be a little "laggy" but otherwise seems ok.