After you select your sites, implementing your communication plan early to get lines of communication established typically ensures the add a site process will go more smoothly. These early communications can help you identify any trouble spots (e.g., delays in funding, turnover in regulatory staff) and address those promptly. You can also encourage your collaborators to reach out to their IRB/HRPP to discuss the cede review process so those sites are ready to move forward as soon as your overarching study is approved.