What Can You Do Early?
Some things can be done ahead of time. If you need higher levels of computers or particular software, get them installed before the migration if you can. Prepare the equipment room with nay required electrical, data, and HVAC needs. Start examining policies in circulation. A new system will not have all of the same functionality and options. Depending on what is available in the new system, policies, especially circulation policies, will most likely have to change. Additionally, this is a great time to change policies that will no longer make sense. Anything you can do ahead of time will make your life that much easier during the migration.