Here is an example you could follow to help with your Windows 7 Migrations. I had written this as a base process for my own Migration and it helps to have the plan set in stone! Feel free to copy it, modify and tailor it to your specific migration and this should help at the least!
Example Windows 7 Deployment Process
Note: The following sections will be performed by the PC technicians for the following day’s deployments.
Note: If number is insufficient for expectations make some calls / check lists to see who can be scheduled.
Note: If the drivers for this model have not been captured, plan on capturing them once computer is reimaged.
(optional / creation of Helpdesk incident)