how will i know when the upgrade is complete?

The upgrade requires the download and installation of three packages, the device will power cycle after each package is installed.  It is only after the third package is installed and the device power cycles (setting up the new operating system) that the icons will be updated on the home screen.  You may also verify the new version under the device settings menu, go to Menu > Settings > About Phone > Android version 2.2.1. Be patient after the final (third) package install, as it will take up to 10 minutes to reboot.