As a matter of interest I got the upgrade reservation app on 30th June 2015, did the reservation, and on 8th August I was informed that the upgrade was ready for me. It took about one and a half hours to run, including several re-boots.
In 2 other posts I mention that the CD/DVD was not recognised, and my iTunes did not recognise my iPad. Both posts relate how I overcame these problems. 10 now running great.