Migrating from Hosted Exchange to Internal Exchange

Until now, my company's Exchange mailboxes have been hosted with GoDaddy. We finally received budget approval to build our own Exchange 2010 server and migrate to it. The problem is we don't have time to migrate everyone at once. We have to create .PST files and copy all the GoDaddy email items to the PST's then re-copy to the new internal Exchange server. With 100+ employees this can't be done quickly, so for a period of time, BOTH the GoDaddy Exchange system and our new internal Exchange system have to "coexist". We have some employees still connecting to GoDaddy and some connecting to our new Exchange server.

The part that has me stumped is what to do with Autodiscover?  Currently our external DNS is setup with an A-record that points autodiscover.ourcompany.com to GoDaddy. Even if I manually create the new accounts in Outlook on our new internal Exchange server - Autodiscovery executes in Outlook every few minutes and tries to connect the new internal accounts to the old GoDaddy system. This obviously causes major problems.

I'm not sure if I should just remove the Autodiscover DNS record until the migration is complete. Does that create problems with the folks who are still on GoDaddy?

Any advice is greatly appreciated, thanks.