http://technet.microsoft.com/en-US/exdeploy2013/Checklist?state=2419-W-EABEAgAAQAAAAQECAQAAAAg~
So I'm about to do this, but the guide doesn't mention 2010 really, will the move affect any 2010 functionality? I will likely need months to migrate all users from 2010 to 2013 and am nowhere near ready configuring Exchange 2013 to start receiving emails (I publish Exchange in TMG), does that need to be configured prior to moving this mailbox as well?