Here is a quick simple command you can run to add a mailbox database copy with the lagged copy time already set so you don’t have to go back and set the lagged copy setting after the seeding.

The below command is adding a copy for the mailbox database named “DatabaseName” onto the server ‘LagServer’ and the lag copy is set for 7 days behind (The maximum you can increase this to is 14 Days)

Add-MailboxDatabaseCopy –Identity ‘DatabaseName’ -MailboxServer ‘LagServer‘ -ReplayLagTime 07.00:00:00