1. Verify you're ready to upgrade. Complete the Marketing Cloud Connect prerequisites, including enabling subscriber key, before upgrading to Marketing Cloud Connect.
2. Schedule the upgrade. To schedule the activation of Marketing Cloud Connect, open a support case in Help and Training portal. Ask to provision your account for moving historical tracking data if needed.
3. Move unsubscribes from the hidden list to the All Subscriber list. To retain your subscribers' opt-out status, retain and use the opt-out record already stored in the Marketing Cloud. This information, including the unsubscribe date, is retained in Marketing Cloud. Insert it into the All Subscribers list for use by Marketing Cloud Connect.
4. Install Marketing Cloud Connect. You're all set to install Marketing Cloud Connect. Once installed and tested, you can immediately send from Connect.
5. Migrate Static Historical Tracking Data. Tracking data is still available in the Marketing Cloud. To preserve tracking, migrate static historical tracking data from v2 to Marketing Cloud Connect.
6. Uninstall v2. After testing Marketing Cloud Connect, uninstall v2 a week or two after you are comfortable using Marketing Cloud Connect.