POP3 to Exchange Server Migration

Hey guys i've got a question. So i have a client who is using a hosted solution and accessing mail through pop and would like move Exchange 2013. I'm trying to come up with a way to get this done in a staged manner. they already have an internal AD infrastructure setup.

So here's my idea:

1. create a public sub domain example temp.domain.com with mx record of course.
2. add sub domain as alias to all accounts user@temp.domain.com
3. set the default domain (domain.com) as internal relay
4. set sub domain as authoritative
5. Connect users outlook to Exchange
6. setup forwarding on the POP account to forward to user@temp.domain.com
7. Disconnect POP account and import pst to exchange mailbox.
8. Switch MX once all mailboxes are moved

Does my plan sound plausible? if not, any suggestions would be greatly appreciated.

Thanks.