Migrating to SQL 12 should be rather seamless. Getting everyone on the same version will make support and maintenance much easier. This will be the first time since v1 that everyone will be on the same version. Whether it is cchit, mu or icd-10, no EMR company has had a choice but to upgrade.
Four months should be plenty of time to upgrade. It is really only a matter of downloading v8 and running the installer, codifying the insurance.