In fact, this is a highly recommended approach in which we suggest that you start archiving the moment you are on-boarded so all mail from that moment on are safely secured.

After that, you can work out a migration strategy, which includes what data to migrate, which users to target first, what methods to use, and so on.

You may also have to create a team to plan, supervise, and execute on this. Importing historical data does not interfere with the live archiving.