Welcome Page upgrade process puzzler

Here is the issue. I have an environment that has deployed a corporate welcome page using organizational desktop policies under 6.5.4 and that works fine.

I want to deploy a new welcome page for ND8 that users will receive when they enter their newly upgraded client and not a minute before (it would be very confusing for a user to get the ND8 welcome page while still running ND6) likewise I don’t want a newly upgraded ND8 user to ever have the ND6 welcome page.

Here is the problem. Even if I use an explicit policy for the upgraded users I can’t time the transition perfectly to coincide with the upgrade.

What I’m contemplating is, shortly before the deployment begins I will clear out the current policy so that it is no longer enforced. Then I will modify the bookmark.ntf that I’m rolling out to have my new welcome page as the default. Once everyone is deployed I’ll go back to using the policy.

Keep in mind that I can do anything to the workstation/ini at install time but after that it becomes more difficult.

Any ideas???

Rob