When you delete the group, you should be able to recreate a user of the same name immediately. The 5 day wait period only occurs when you delete a user and try to recreate a user of the same name. Deleting a group or email alias does not lock out that address for 5 days like it does when deleting a user.Also, Google Apps seemed to have removed the online IMAP migration tool from within the Domain control panel. So the email migration has to be done using the Google Apps Migration for Microsoft Exchange utility .
Once you install it, the setup is like the screenshot for migration from gmail:
In case it asks you for changing the consumer key, you have to log in to google apps as webmaster and copy-paste the new key.
The users csv file should be of the form
(Please note that the @google.apps.domain is not required for the second field.)
Unfortunately, this tool takes a lot of bandwidth, needs the computer to be on all the time it runs, and is much slower for gmail to gapps migrations than the online IMAP migration tool. A sample run is:
Info:Start local time is: 2011:06:01 13:56:12
Info:Migration start local time is: 2011:06:01 13:56:12
Start: Now migrating user=**********
Start: Migrating Email for store=**********
Start: Migrating 105 messages from Folder [Gmail]/All Mail for store=**********
In progress: Migrated 100 out of 105 messages from folder [Gmail]/All Mail for user.
Success: Migrated 105 messages from folder [Gmail]/All Mail for store=
Info:Migration end local time is: 2011:06:01 14:25:19
Info:End local time is: 2011:06:01 14:25:19
So it took half an hour for 100 mails.